Miners can choose what transactions they want to include. If they don't want to include any transactions other than the one that pays them their 25 BTC, then that's their choice.
Haha what an effective and good answer! Good job.
PS. Why don't we have a tip bot for comments on this forum?
There is no tip bot, but I guess the Bitcoin address of the users are listed on their profile page, so we can tip anyway.
It takes a bit longer than tipbot, but if you really want to tip, that works.