Honestly there are a ton of problems with Blob ranging from the fact that it is a very weak antagonist (Blob basically only wins if the crew is stupid) to the fact that it's probably the least interesting antag to fight against, while also forcing the entire crew to drop what they were doing to go fight it. But this is a discussion for another thread.
This almost entirely a problem with Blob being incredibly weak. Mechs are fine where they are, and most of the time they suck big dick because A) most people haven't piloted one before and b) most antags can outmanuever them quite easily unless said mech in question is a Gygax or Phazon. Not to mention ways to ensure Robotics can't even build them by sabotaging mining.