As materials have improved, every part of a bike has become stiffer and that includes cranks and chainrings. Your problem could be any number of things including the frame, crankset, front derailler, bottom bracket, and chainrings. I would tend towards the cheapest solution which is first making sure what you have is tuned properly and only then looking to replace parts.

I just had another thought. Try grabbing your crankset by each arm and see if it will wiggle back and forth towards the frame. If it does, your bottom bracket needs to be adjusted. That play alone could cause the rubbing you are experiencing. Also check to make sure your chainrings aren't bent.

As I previously suggested, a simple bottom bracket spacer which will move the crank away from the frame should cure your problem and only cost a few dollars. If you have the upgrade itch, I won't try to stop you but there's no way I can guarantee you won't experience the same problems requiring the same solution as if you had kept the original parts in place.