They prefer to leave things within the market so it adapts to demand and supply. If you think about it, the only items which really sell in the manner than you want are the things like tiles and paint in that stupid neohomes shop that nobody really bothers with and I don't think most people even know exists. Pretty much everything else is affected by the market.
ZYea for sure. I can definately see why they would want to let things be through supply and demand. I just think that it's about time Neo has seriously considered how badly everything's inflated to. The Hidden Tower Books avatar was intended as a NP sink, but didn't do too much (same with the wishing well).
There's just not enough consumption on Neopets. In fact, there's a lot of useless junk on the site (like the neohome stuff you mention). And for the items heavily consumed, it's limited to a few items.