I'm sorry I disagree Hula I think too many things for kids does make them spoilt.Where do you draw the line? You have to draw a line somewhere,how many toys does a kid actually need?
A constant stream of toys throughout the year is spoiling however clever/manipulative(ie not throwing a strop to get them) a kid is. If they are used to them (which they will be as it's a regular event) they are expecting them so they're spoilt.
Keeping a room tidy looking after toys does not an unspoilt child make. That is a character thing. I have twin boys they get the same one is extremely tidy the other would happily live in a pigsty.
Oblomov don't despair all 6 year olds are a pita at times/ a lot of the time it feels like you're banging your head against a brickwall because kids are designed to challenge their parents. By being firm and consistent he'll get there.
Re the appreciating toys thing some kids just aren't into toys in a big way all kids have different brains. 1 of my twin boys 6 has never been into toys not asked for any, this Xmas was a nightmare he wanted nothing so we got him a globe,craft stuff and books which he loves. The other would have happily found room for the entire Playmobil/Lego catalogues but he was happy with suggesting just 1 thing.
Have you tried packing away lots of toys into the attic and rotating. Also tidying his bedroom so they're all out of view(less overwhelming). Also can you start him off with play ideas.
I also ban TV sometimes now mine are older(they want it less anyhow)it's amazing what they'll play with when there is nothing else to do.
I also have the nothing else out until you've tided away rule,dtwin1 will happily play with a stick if it meant he didn't have to tidy
I also find the no new toys between bday and Xmas rule good. It's hard as mine are Xmas/Sep bdays but they do and half appreciate their new toys at Christmas. I also put some Xmas toys away new and get them out when they're ready to play with them properly not all at once.
My lot also tend to have less but more pricey(cuts down on storage probs too)I think a lot of the trash in shops is a total waste of money,not surprised when kids aren't interested in them for long. It's the throw away society, kids are being trained to throw away and move onto the next toy.