Why did the Engineering Bay lose the ability to lift off in Starcraft 2?

Solution 1:

I'll take heed to the subjective nature of this question but I'll share my speculative answer anyway.

At the time of writing this the engineering bay costs 125 minerals, takes only 35 seconds to create, has 850 health and has +1 armor. If the engineering bay could lift off, you could have a pretty durable scout that's fast and cheap to create. This could open up a whole slew of possibilities for Terran.

Solution 2:

Giving a building the option to fly is definitely an advantage for terran. The more buildings that can fly, the more buildings you can use for scouting (both for intel and siege tank spotting), for winning base trade races by lifting and hiding in the corner, and for creating reconfigurable wall offs. I don't think allowing the engineering to lift would fundamentally change the nature of the game, but it would be a slight benefit to terran.