But from a design point of view, I gotta go with Firaxis. There were multiple times where if I had 8+ units, that there was multiple turns where I had units that couldn't/didn't do anything, and fairly often where I would have to literally sacrifice rookies to explore darken areas. It was detracting, and flooding you with more choices then you'd want to sensibly deal with.
Now on top this with original X-Com, was that it rewarded you more for having less troops. The less troops you had on a missions, meant more actions for the troopers there were there, that means more XP. That means better stats. There also the great challenge play throughs, like the Chuck Norris, or Rambo, where you use only one unit. (Chuck could only use the stun rod, Rambo could use weapons.)
The classes, I dont think we have enough information to judge the implementation of the class system. There defiantly seem to be confusion between equipment being universal equipment and equipment being reserved by class. This might be special actions with equipment + class combo's, or bonus for using equipment + class combos, or free actions with equipment + class combos. None of those are 'bad'. And there are certainly ways that equipment + class combo's can be bad.
From what I've managed to gather about the classes, they're meant to give a framework and direction on how to use your 4 units. They're meant to give you a soft hand on how to handle the game. 'This is my support class, so I dont send him in to do the final kill.' - 'This is my scout class, so he's best at flanking and checking our sixes' - 'This is my kill class, so he should be getting the fire directed at him, away from the classes and doing the kills'.
In the original X-Com, you generally did this class set up anyway. Its not an uncommon to designate one guy as heavy weapons, sniper, forward scouts, medics, ect ect ect. And the original X-Com barely gave you the tools to set up these classes. Heck with its inability to remember load out per unit its practically fighting you to set up these classes.
The removable of Time Unit, I'm neutral on. What it did, it did well, but it didnt do it optimally. Its fairly hard to determine the Time Unit Cost for your end actions for your units.
Then there was unreasonable balance between wanting reactionary fire, and say, ducking when you figure out that several units are in danger, after they've moved. That's not rewarding, thats shooting you in the foot. But these issues are issues that can be addressed and fixed.
I'm quite curious now to play X-Com through again, and really be mindful of how many times, the Time Unit gave me unreasonable no's, not tactical no's, and unfairly punishingly for just happening to not to move the units in the 'correct' order.