Well, you want try some skin before buying it and you will use /tryskin of course... and you will be frozen to avoid using skin without purchasing but if you purchase it you will still have to do /rejectskin in oreder to be able to move, so why not make it like this:
/tryskin RandomID
I like this skin! I will buy it
/buyskin SameID
You've purchased new skin
**Exits the shop
Instead of current way
/tryskin RandomID
I like this skin! I will buy it
/buyskin SameID
You've purchased new skin
**You still can't move because /tryskin command frozen you
Have to do /rejectskin so i can go out shop
Basicly, if you buy skin that u tried, you get unfrozen.