Im not really surprised to see people bashing this game just because they passionaly loathe PGI.
MWO is full of doubtable choices, but sinceraly? It also has its merits. Older Mechwarrios games are also all flawed in thier way, and a modern reaproach seems very welcome.
There are actually very little details right now, we dont even really know how done is the game, maybe its in an early stage and will take some years, maybe its half done and will lauch in 6 months, until they give us more information, we just dont really know what is happening in MW5 development
And about the Mechlab... well its hard to say, because they gave us little info, but i also think its not without merit. The lore excuse is a bad one, but it also has merit. So you have a stock mech. It is possible to reconfig it? Yes, but is extremely expensive and hard to so, depending on what you are doing. His exemple of the Jenners and armor is ***. Armor is armor, its a layer, unless ferro-fibrous doesnt fit because there is no space then its a really easy and simple swap. Endo-steel is next to impossible. You would have to deconstruct your entire mech, but that is the easy part, where would find the structure? They dont just make spares of it, it is something build during the fabrication of the mech, and there is probably 1 or 2 factories that make that structure in the entire inner sphere, if any, because not all mechs got a endo stell variant.
Weapons, equipment and engine, are more on a middle term. Their swaping is not as radical, and there are many (but not plenty) lying around. But even then, what are the odds that the planet you are will have an engine with the EXACT rating you want? Weapons and other stuff where not made modular, neither are mechs (execpt Mercury, but even then), exchanging a weapon requires you to change the chassi of your mech, make fit inside, have someone program the FCS, recalibrate the gyros, and spend a lot of time and money.