Lets see, cPanel is not design for free hosting, it's expensive, they can't give you adequate support and it's causing a lot of problems and downtime. On the other hand there's a lot of other (even free) admin tools out there that could do the job.
I don't see any good reason for keeping cPanel under this circumstances.
cPanel isn't designed for free hosting, yet x10hosting offer it? What does that mean? Well, basically x10hosting are doing a lot of free users a favour and is recognized for it. They're offering cPanel for free which is most likely attracting a lot of members, and that's how x10hosting came to be.
Indeed there are a lot of other panels out there and as you've stated, some even free but then x10hosting won't have as good reputation. Reputation in this case probably doesn't matter, that's what you're thinking but how many more members do you think will sign up for a free control panel?
There are probably others that can do the same job, but maybe again not as good or as easy.
Good reasons to keep cPanel is that x10 are offering it for free to free users, which will gain more members, the more the merier (higher incomes). cPanel is known for it's powerful control panel, and more members will feel more relaxed with it. Other panels won't be able to do the jobs easier, and members may not sign up as they've never heard of the panel before.
CPanel just needs to go, sure there are a few hold outs that like CPanel, but there are other account panels that are more powerful then cpanel and much more suitable to x10hostings needs.
Yes, maybe more suitable to x10hosting needs but never more powerful. cPanel 11 is the most powerful panel available out there, yet still user friendly.
May be there are others that are similar but cPanel just attracts more members and other panels may not.