My suggestion would be to not set yourself up for disappoint and try not to invest time into media which has reached its expiration date.
I understand there are those stern Simpsons fans who have been watching since the beginning. However, as many have suggested above -- the Simpsons really reached it's pinnacle by Season 6 and only remained watchable until about season 8 or 9. As someone also mentioned, singing in earlier Simpsons episodes. Off the top of my head I can name 8 episodes which had musical numbers and those were hilarious (Monorail, the Garbage Man Can, Do the Bartman (which was a separate project altogether), and the Sherrie Boppins episode); but it wasn't a regular thing.
The way I choose to continue to respect the impact the Simpsons had on televisual history is to measure it by the success of it's early writers, challenging ideas, early adaptability and lack of consideration toward censorship (initially). Singing is not the worst thing that happened to the newest Simpsons. Sometimes it helps to shut a program off for about a year and then go back and watch an early episode - followed by a recent episode. Then, you'll get the picture of what the majority of the comments have been pinpointing.
The only reason the Simpsons continues to air is to give Groening royalties (and the new parent company...Disney) and support whatever lifestyle he lives now. His last great production was Futurama which was considerably better ever from it's inception than seasons 9 + of the Simpsons.