Also allowing attributes to increase would explain characters becoming equal to their NPC counterparts, because there are lots of NPCs in the GM's guide that do not have the 'allowable' number of attribute points that PCs are limited to.
As to it being worth more...I don't know, it does provide more 'HP' but skill dice can't bane so I feel like that might be a bit of a wash
Characters has been design to work with the various game systems. NPC:s doesn't use most of the system, they are designed to be something for the players to interact with.
Yeah, I don't really buy that. If a Redrunner can have more stats than ANY PC elf, with no fiction reason for why, then that's a problem. If they wanted them to have X die pool and be Y effective, they could have just given them the skills to reflect that. But lots of /mook/ NPCs have bigger stat pools (and to be fair, some have less but I'm okay with PCs being top tier for their people). I can buy it for the occasional 'special' NPC, but when it's grunts? That doesn't make any sense.
But skills cost more for each skill level you take. Skill level 4 will cost 20 xp, so that is something that needs to be taken into account if designing an attribute increase system. If 20 xp is the cost to increase an attribute, well ...
Oh, clearly the cost would have to be a multiple. Probably 12x - 20x the level you are buying to. Which would, in all fairness, make it mostly a moot point...who's going to not advance the length of time it would take to reach 40-60 saved xp? That's possibly an entire campaign.