Being all about hot keys and speed is not the same as requiring more tactics nor does it mean the game is deep. Starcraft is almost purely a game of speed. What are you defining as skill to claim that SC1 is the best RTS in terms of how much skill it requires to play and what are you comparing it to? That's the same defense I hear every time someone argues for Starcraft. Don't get me wrong I played Starcraft for a long time and still break it out on occasion at LAN parties. But it is one of the simplest RTS's ever made and requires very little strategy. The fact that my brother can actual win at it is proof of that. :p
"Having a formation button would make it too easy"? So having a lack of normal RTS controls is now a feature? High/Low functionality is certainly nothing new and to that end Starcraft 2 doesn't even do that good of a job at it. Even when Starcraft 1 came out, it did NOTHING new. It however did it very well which is why Blizzard succeeds. I have to ask at this point what other RTS's you play because I find most people with this argument for Starcraft have really only played Starcraft for any length of time.
If you honestly think Starcraft requires more skill to play than any other RTS, I'd be happy to challenge you to one of those other "lowly" RTS to put that to the test. Theoretically you should only need a basic understanding of how the game works to beat me with your Starcraft refined skills, right?
Here's a list of things found in multiple other RTS that greatly increase the depth of the game yet Starcraft lacks. Let's start with the basics.
1. Superweapons (IE nukes). Given your argument against massing units, you should like this one. Superweapons are a key in any strategy game. You don't even necessarily have to use them. It's the fact that you COULD use them. Supreme Commander on is one of the bests in this regard. Nukes were truly a weapon to be feared. The fact that your opponent COULD use them required you to either account for them in your base defenses or be prepared to lose everything. The SC nuke (1 and 2) is a joke. It's more of an annoyance than a weapon of mass destruction.
2. Play Area/Map Size
While this is certainly not a requirement for a good RTS, I've certainly never played one where I've said "I just wish the maps were smaller". Small map sizes has little to do with tactics and more to do with speed. Proper Zerg Rushing requires a specific memorized build order but even with that it only works because the maps are so small. With larger maps, unit speed and view distances become a much larger factor as well as proper recons and patrols. Sins of a Solar Empire is probably champion in this regard. When you are playing on a multiple star system map, taking your fleet to another star system to do battle means leaving your planets all but defenseless. Getting your fleet back to friendly territory is no small order. There's no Arbiter recall or Nydus canal. You've got to hoof it back the old fashioned way.
3. Weapon Ranges
Starcraft barely scratches the surface on this one as well. By most standards the siege tanks range is laughable. Check out Supreme Commander or Company of Heroes to see how Artillery is supposed to work. There's a reason we have things like MLRS's in real life.
4. Unit Experience
Here's another category that's become pretty much the norm and is completely ignored by Starcraft. Unit kills lots of things, unit gets better at killing. Pretty simple concept. The better this is implemented the more you start to value units. No more wasting a horde of units just to take out an ancillary resource production facility. I find this one especially amusing since you make mention of the attention to microing. I'll spend a lot of time microing a high level unit to get him in and our of a combat situation as quickly and safely as possible.
5. Interactive/Destructive Environment
This one is HUGE when you want to start talking about depth and tactics. Company of Heroes/Dawn of War is unmatched in that regard although World in Conflict isn't bad either. There's no such thing as just "hey troop go here" or "oh, I'll do attack move to be safe". You want your troops to make use of cover. Company of Heroes is FANTASTIC in that regards. Cover can make or break a battle.
6. Multiple Damage/Resistance Types
I'm not talking about just calling it different things like Starcraft does. I'm talking about units doing multiple types of damage and having to account for it. Warlords Battlecry takes the crown on that one although Earth 2160 gets honorable mention. With 7 different types of damage (each with it's own effects) and corresponding resistances that game was unmatched for having to properly counter something. If you take a group of fire mages and trying to attack Daemons (which have like a base 80% resistance to fire) your mages are going to get raped.
7. General/Hero units. Sins of a Solar Empire (SoaSE), Dawn of War, and Supreme Commander really shine here. There's no greater "oh ****" moment than seeing a General/Hero unit coming right as your troops are deployed. A single capital ship in SoaSE can hold off a small fleet on it's own, especially when leveled up. A Dark Eldar Avatar (Dawn of War) can lay waste to your whole army if you aren't careful. A single experimental unit (Supreme Commander) can level your base if you aren't careful. This ties in with with unit experience as well. If you find a hero off on it's own, you had better hit it while you can. If you wait until it regroups, that's going to cost you.
Once again, I wouldn't say Starcraft is a BAD game by any means. It certainly has it's place is gaming. But I play Starcraft when I'm just wanting to get some quick gaming in. I play SupCom or SofSE when I want to settle in and really play strategy. It's like comparing checkers and chess. Sure, checkers technically requires some skill but it's pretty limited in depth.
XM have you ever watched a Korean SC tournament?
Yes. Have you? I've played against a few Korean players as well. I got raped playing against them. Why? Not because they had better tactics. Because they were faster. We had the exact same strategy. They just executed it first.