You don't like the crafting part? That's the only way to keep lower stones common and higher stones rare though, I think.
Firstly i'm not sure anyone enjoys the crafting component of this upgrade system, at least those who've I've had a chance to discuss it with and secondly; on the topic of upgrading systems, for what player base are you speaking for? Cashers, farmers, casuals, hardcore?
There's no need to upgrade lower equipment because there isn't enough demand for it -- besides there is no inherent value in doing so since most of low level content can be breezed through with +0 equipment. I understand the pool of players that participate in kid budokai may beg to differ, which in any case they can benefit from an easier system being implemented anyways.... at least if that is the intention. Watch sales and player count rise when +15 becomes the norm. I can guarantee it.
Upgrading lower tier equipment is fruitless and a pointless endeavour mainly because there isn't a diverse enough population any longer.
This crafting idea however, allows for accumulation and the expansion of value through the recycling of resources. I can subscribe to concepts like these being implemented.
But it's really just unnecessary and detrimental to a DBO server.
I think.