Without saying that any particular instance of Mongoose changing the technology is bad (for one thing, I still only have second-hand evidence that they've actually done it), changing technology is potentially very, very damaging to a setting. It shouldn't be done without considering the ramifications.As near as I can tell, every single instance of the Traveller rules has changed the technology to some degree.
Given that, why is Mongoose doing the same thing so terrible?
The most egregious example is probably TNE's HePlar drive. Not so much the drive itself, but the concommittant absence of thrusters. If thrusters didn't exist and never had existed, the entire economic underpinning of the universe changes retroactively. Though I admit it helped a lot that GDW ignored all the ramifications of that particular change. MT changed the fuel consumption of jump drives. Again, they didn't explore the ramifications of the change; that a ship was now able to carry enough fuel for two five-parsec jumps wiithout refuelling, suddenly making ten-parsec gaps in the stars almoast irrelevant. Again, I admit that it helped a lot that MT ignored the ramifications. But ignoring the ramifications of the technology is, IMO, sloppy and sub-standard work. GT's 20% reduction in interior space for streamlining suddenly made streamlined ships markedly inferior to unstreamlined ships. The ramifications would be that unstreamlined ships and orbital facilities would be a lot more common and streamlined ships a lot less common.
So to answer your question, Mongoose doing the same thing would be terrible because previous versions doing the same thing was terrible too. Sorry, may be terrible; some changes won't make much of a difference and others might even be an improvement.
Hans