Quoted from CrazyLevi:Why not? Because it's a bad idea that nobody wants*
It's been tried many times and it never catches on because it's a stupid idea, and stupider than ever now that the majority of games are being sold to home buyers.
Home buyers don't want them. Storing extra populated playfields in boxes takes up almost as much room as a game itself. Nobody wants a game room full of boxed playfields and one functioning game. Nobody wants to spends time swapping out playfields when they are drinking with their buddies. Nobody wants to say "hey check out my cool game room!" only to show off a room to their buddies with one generic cabinet and a ton of musty playfields in boxes.
Ops don't want them. Ops need equipment that earns, not a bunch of playfields in storage. Ops need attractive equipment to lure in dollars, not generic cabinets.
Both ops and home buyers have been given NUMEROUS chances over the past 45 years to latch on to the brilliantly innovative idea of "swappable playfields." Conversion kits. Pin2k. Doctor Who and Congo in the 90s...the "playfield swap" idea has ALWAYS failed and it will always fail yet this failed concept is always a rock star in every "innovation" thread.
*Also...playfields ARE swappable. You think Stern or any other company completely changes their hardware and production system for every single game? Just buy a bunch of populated Spike 2 playfields and get a Spike 2 game and swap to your hearts content. Boom!
Like the man said, I don't want it. Just too much work for me anyway. Even if you make it perfectly swappable, I'll still need storage space, extra parts, tools, some kind of workshop and the ability to put things together. Then, where's that instant feeling of pressing the 'start' button to play games right away? "Sorry babe, you can't play Mando, I've swapped the pf for GOT, maybe next week if I have the time?"
Nah, not interested!