Wouldn't it be awesome, if you could take direct control of units in the middle of a battle? Like when there's a marine-hydralisk conflict, you can "Assume Direct Control" of the marine and the game's turn into a FPS? What do you think of it?
I wont say it's a bad idea, but it wouldn't work in a RTS like SC2, especially with a marine since it would die in less than 2 sec if the opponent mass targeted it. Also, you would be giving up your ability to micro he rest of your army, allowing your opponent to more easily kill off your entire army. However, they do have a First/Third-person shooter function built into the map editor, so you or others could create maps specifically designed to play like a first/third person shooter game.
Yeah, it would be bad for Terran gameplay. But what about zergs? Maybe a zerg, when taken direct control by the Overmind, they'll get increased HP/stats so they wouldn't die so easily. It's simply an idea, though.
'Cept the Overmind died in SC:BW, so it would actually be under direct control by Infested Kerrigan. But giving a unit more HP/stats when under direct control would basically be saying it's a hero, which most SC players don't want for standard online play. The idea could be useful for custom games, but for standard maps, I'd prefer sticking to normal RTS gameplay.
Would be great for the line defence style maps, though. Imagine being a Ghost on some hill. You have Towers and other units that you can command and stuff, and your opponent has the same. I'd play it over and over.
I agree for standard map play a big no no. But for anything custom or maybe even an entirely new game based on the SC2 map editor and engine sure add it in. It should be really interesting what people come up with.