Am looking forward to September for our 10th stay in Arillas (once at the Horizon and 9 times at the Kaloudis Village), and since our first visit there in 2003 have noticed various changes, mostly for the better. I suppose the supply of sunbeds is very much down to the law of supply and demand - market forces, so if there is a profit in it, there they will be. The regulations Dimitris has outlined seem well designed and if complied with should avoid sunbeds becoming an annoyance.
As mentioned by others, there is still plenty of beach without sunbeds if one is prepared to trek a little way, and again there is nothing to stop anyone plonking their towel down where they will.
Pat