Hi there. First posting and i am starting with grumbling. Sorry that for.
Those poll question has nothing to do with the answers. You did answered the question why you play those old games. But you don't need emulation to do so. You can buy the old systems and games and can have the same fun.
My reasons for emulation are:
First at all, time saving.
I can save time by not building up my plattforms every time i like to play. It is very comfortable having all of them on one machine and switch between them by clicking.
I am saving space in the living room, all the engines, controllers and power supply units are good stored and stay in their good condition, not been played to death that fast. On some special events the real things they are used to remember those good old times. So the next reason for emulation is:
Save the old systems in good condition.
The next time savers are the "save anytime" functions of the emulators. Yes, they can be used for something you may call cheating, but used properly the give me the possibility to play even for some few minutes. You know, ten minutes until your train/bus/taxi arrives, the few minutes your girlfriend needs to get dressed with the right clothes for going out... Good for doing two or three fights on RPGs, driving some laps in racing games, getting some points in your jump'n'run. Thinking about it, this is my personal favorit for using emulation. (Especially when you can start and complete Secret of Mana while your girl evaluates the perfect outfit... Just kidding...)
Directly connected to that is mobile emulation. Riding a train and anybody got his ear-plugs in, not interested in small talk? A lot of people are reading books, thats my time to get my GP2X out and start an emulation.