And if the engine is taken out the mech becomes a useless metal coffin. That's a really bad idea. The middle currently has little to nothing there so you don't have to worry about it being cramp.
Eh, It depends on your logistical situation. f the pilot survives, they can catch a ride back to base, Hop in a new mech and get out to sthe frontline again without breaking a sweat. That was part of teh reason why the Sherman tanks and western tanks in general put so much into crew survivability, Because if you have the crew and the tank suffers a failure, and teh crew is alive, they can be back on teh frontline in a matter of hours, compared to trying to fix a Mech up and get a new pilot.
If the Engines fucked and the pilots alive, The pilot can get a new mech and the old one head sto the shop, If the engine is fine and the pilot is dead, You still need to recover and wash out the old pilot and fix the damage, and then wait for a new pilot.
Of course, this philosophy of design requires you have a steady supply of tanks, like allied powers did in ww2, but considering the price tag and simplicity, its not unreasonable for our wealthier customers to manage something similar.
Once you hit Battletech levels of "This is fucking expensive to fix" Then you Let the squishy meat bite it, but in general the pilot is the more combat important part for a war.
of course, For tanks its an entire well trained crew with teamwork, For mechs i'm not sure if we are working in crews or if the quad is single pilot, so that might change the math.