I like recreating the experience of playing these games back in the day with the actual hardware and controller hooked up to the tv. And having an obscure conversation piece by my TV. When I use emulators, I only use them on my pc, and when I use them on my pc, I am playing the game with my keyboard at my desk. I know there are simple ways to remedy this and get my pc hooked up to the tv and get an xbox 360 controller or something - but at the end of the day, it gives me delight to look over on my shelf and see this crazy lump of plastic that I bought, and then sit down in a comfortable spot and mess around in the living room or wherever.
The hunt for a good deal on the lump of plastic is part of the fun as well. And when you own the actual game and play it on the console, you wind up having a deeper experience. When I play on emulators, I might start using savestates, and I might just flick around from one game to the next every 10 minutes just because it is so simple and it's all easily available in a directory. For some consoles, especially cartridge ones, you might just be limited to the 5 or 10 games you own for the system, so you put more time in them and experience them to a deeper level than you would if you had an internet rom database at your fingertips.
Having the physical product and recreating the experience is significant to many people's enjoyment. Just look at how many people go out of their way and to great expense to build mame cabinets!