There are a couple of trends going on in the computer world and the world in general, and I think Clement and Mark have picked different trends to follow and cater to.
Non-geeky or only semi-geeky computer users get tired of Windows' flaws and want something more secure, but want to retain Windows' GOOD POINTS... the ways in which it allows them to GET WORK DONE. Clement is trying to offer these people Mint as a migration path.
He got me... when I experience a virus attack I picked up on my favorite music forum, I knew I needed an alternative, and it would probably be Linux of some kind. I found Distrowatch, and was bewildered by all the different distros. However, I did know some friends that had tried and liked Ubuntu. But nearly everything else was totally unfamiliar. So I went down the Distrowatch rankings reading reviews until I got to Mint, and the descriptions of Mint were EXACTLY what I was looking for in a Linux Distro.
1. Large distro (and in a sense being related to Ubuntu makes it larger). I don't want something that's going to disappear next week.
2. user friendly- using the terminal is not absolutely required.
3. extra bug fixing compared to Ubuntu
However, there is another trend going on. A lot of young people are using smart phones for ALL their internet browsing... they LOVE their phones. And I can see that if they HAD to use a computer, they MIGHT be more attracted to something that worked more like their smart phone that they spend so much time on. This is what Mark is focusing on and it makes sense in a way... but the problem is, it's a gamble.
The reason they fell in love with smart phones wasn't the interface... it was size and portability. I don't see a different interface luring them back. But maybe it will... if it does, Mark's gamble pays off big time.
Clement's choice SEEMS safer, but really it's a gamble too. If Linux Mint becomes mostly popular with an aging demographic, that demographic will eventually SHRINK.
However, schools and workplaces will probably continue to use computers, forcing people to retain familiarity with them.
Because Linux is used in servers, they have IT personnel that are familiar with Linux.
So if the desktops were converted to Linux too, that wouldn't bother the IT techs at all.
And if Mint and Ubuntu retain enough inward compatibility, they could be used in the same workplace without too much trouble, using the same software.
And people could use whichever interface suited them best.
Really whether something looks dated isn't the issue...
the issue is whether it gets in the way of doing what you want to do.
If you use smart phones all the time, and shifting to a more traditional interface gets in your way, then Unity will probably be a good thing for you. For people who migrated from Windows, they really don't want the new OS to be THAT much different- that would get in the way of getting things done. "New" is only really good if it's also really "improved" as far as getting things done.
Several things could happen... if Unity catches on big time, I think Clement will want to do a Mint version.
Or, it's possible it could bomb, and maybe Clement and the team will get tired of having to make too many big changes...
they might pick another distro to base Mint on. Maybe Mint Debian is the wave of the future... or maybe the future for the more conservative form of Mint.