The endgame crafting items are often upgrades for darklight equipment before you get the allagan items. You often only take a crafted item if that slot isn't filled by mythology items.
Since the chance getting an allagan item in coil is quite low in most cases and even more if you have to roll with another healer, dps or tank crafted gear is an excellent upgrade.
And yeah it is a high price but it wasn't ment that you could get all decked out in crafted gear a couple of weeks after this game got out.

You do know that if you do for example castrum with a static group you could easaly do it within 30 minutes wich would give you 100 tomes. So for making the robe wich would require 1125 tomes like you said in op, it would take 12 castrum runs which is equip to 6 hours of dungeon runs.
Or to make it easier if you do AK or WP to cap your myth you would get 1000 tomes if you do WP 10 times to cap out which you need to do anyway.