Solo mining is best for the the network if you keep up with the software updates and you have the time to do your own fee policy. Most people don't want to bother with that, they're ok to delegate that power to others.
Staying up-to-date can sometimes be a bad thing:
Hello everyone,
there is an emergency right now: the block chain has split between 0.7+earlier and 0.8 nodes. I'll explain the reasons in a minute, but this is what you need to know now:
- After a discussion on #bitcoin-dev, it seems trying to get everyone on the old chain again is the least risky solution.
- If you're a miner, please do not mine on 0.8 code. Stop, or switch back to 0.7. BTCGuild* is switching to 0.7, so the old chain will get a majority hash rate soon.
- If you're a merchant: please stop processing transactions until the chains converge.
- If you're on 0.7 or older, the client will likely tell you that you need to upgrade. Do not follow this advise - the warning should go away as soon as the old chain catches up.
- If you are not a merchant or a miner, don't worry.