I don't think there's anything wrong with recycling characters so long as you own everything that comes with that. If people remember your recycled character and don't want anything more to do with them, you might find your RP limited. But that's on you. If you're cool with that, why not? You don't owe anything to anyone.
I have reused characters before if I feel like there is still story to tell with them. If that's where you get your enjoyment, do what makes you happy. I haven't played a MU* for quite some time and if I did come back, I'm probably going to recycle a character I'm familiar with to get back into things more easily.
You do you. Have fun and don't overthink it.