Really? I had the opposite, I had to out of my way to get the tentacle parasites and diliberately stall for them to attach so I could see them in action. Also really wasn't really a giant maze, the indoors can be ignored. The parasites only start attaching when they're low life it seems, if you focus them, they shouldn't. And I don't think they start attaching until someone's loses part of their bikini from the other enemies, which only happens if they manage to run away and you don't kill them. Plus in regards to the restricting vision/slowing down, you can switch your main character around, unless your whole party was infested.