This would be handy, and I understand the predicament.
I often find that I require to quickly change between clothes for roleplay purposes among other things, and 10 slots isn't allways enough, not when I have some that I will use a lot more than others.
I generally have 2 clothes that I will wear as a normal thing, my own unique combination that I wear regularly. I also have combinations that are used regularly for different purposes. Mainly for roleplays, since one of my most active roleplays has me wearing 2-3 different combinations for varying reasons, so I keep those on there.
This happens with each common roleplay I do, and occasionally, I get to the point where I have all 10 filled, and I need to very quickly, as in, walk behind a building and change in under a couple of seconds, change clothes. Which, can't be done when I have 10 slots allready filled that I'll be using more often than this quick one-time use temporary thing.
tl;dr, I've filled up my 10 over time and an extended grouping would be handy for those quick change moments.