Ah yes, the old "I do it because everyone else does it" excuse. It's not the system that's broken, it's every individual politician who chooses to follow that path. "You won't make it in industry X unless you do Y" is pure self-serving bullshit.
Do I think lobbying (as a system) needs to be fixed/changed/altered/tweaked? Most definitely. But making it outright illegal is like making drug use illegal, people are still going to do it regardless. At least with it being legal, we can keep tabs and utilize harm reduction when necessary.