Now that that is out of the way...

To the OP, the cost of doing business half *** if drastically higher than doing business the right way I suppose, even though you may not recognize the cost of bad business until something like this happens.

The only reason I can think of for the seat being a more severe fine than the landing gear is...

Landing Gear - less likely to break but if it does, it could injure quite a few but most likely, a gear up ldg wouldn't injure anyone that bad bring bad flack to the airline mostly. In this case, the FAA could point the finger at them and dodge the flack.

Seat - More likely to break and even though it would probably only injure a few people, they would more than likely be injured and of course file suit against the airline saying that they were injured and bring more bad flack against the airline and the FAA too (being the governing body that is supposed to regulate them).