I've slept on the summit 5 times now... The last time was last summer as I ended the JMT, and I was the only one up there.
Absolutely… keeping an eye on the weather is a MUST. The other thing to consider is water – staying on the top means carrying your pack the whole way up, with enough water to get you thru the night plus the next morning ‘til you get down to the first source of water. That means a HEAVY pack.
For me, it’s worth it. Each time was so special... so memorable. Yes, it's cold, windy, and not the best sleep, but the sunset, stars and sunrise are worth it. There are some really nice “shelters” dug out and reinforced behind the hut.
ANY time you reach the summit there is that sense of accomplishment, but, for me, staying on top completes it. After the last of the hikers head down and the summit is still and quiet, there is such peace and beauty, looking out over the Sierra, it’s humbling. It is truly spiritual.