If you only PvE, if you only Life Skill, if you only PvP 100 slots are fine, the problem comes in when you do more than one of those 3.  I you make full utilization of everything BDO has to offer you need ~300 crystal slots.  

If crystals stacked inside of the crystal inventory the issue would be solved.

Yeah, with the addition of the new Lifeskill Crystals and extra Crystal Slots the amount of presets and crystal slots is too low.

For Artifacts, at least we can set up an artifact/lightstone combo on a character and leave it outside of the preset, but with crystals, there's no way around using the preset system.