Just rejoined the game as a subscriber after having un-subbed when it went f2p ~3 years ago. I honestly didn't think the game would survive that, and tbh there are aspects of the game that I still dislike and the basic content is still similar to that I enjoyed 3 years ago across all 8 characters in my legacy, but without much class specific content 50+ ... yet.
Back to the matter at hand, I'm in the same boat at the OP, finding that XP pushes me too quickly beyond content before I've had opportunity to play. I play the game to see it all and certainly don't consider it a race. and the same goes for any MMO. In World of Warcraft at least I could stop experience gain while enjoying the content, at least in the (at any time) current expansion with there's still players willing and able in group finder and such. This has always been the problem with heirloom gear in that game, where XP would attract another +50-60% xp, but at least there was always an option to control that - which I've often used - and level at the pace I felt most comfortable with.
As others have said, I surely realise I'm in the minority, but I'd certainly support a feature which put me back in control of how fast xp is gained for my characters. The desire to gain xp as fast as possible is not universal.