I'm excited about the concept of reverse engineering things to create unique items. This potentially means there will be loot drops, and therefore tangible rewards for being an explorer type character.
I mostly haven't been a crafter in IRE, focussing on tradeskills instead (gathering and item creation).
Edit I enjoy when there is a crossover between the types of playstyle. For example, if knowledge gained while exploring helps in pvp, social or trade. I enjoy pvp more when there is some other implication, be it fighting over a resource, a personal feud or a political one.