A level 15 is not going to be doing much exploring, quests, missions, or helping people. Some, yes. A lot, no. A level 75 is slightly (understatement) more able to do so. Whether you have fun in the process of exping or not, it's kind of a necessary stepping zone in order to be able to do some of the more "generally considered fun" things.
If exp is fun, fantastic. However, what *makes* it fun for the majority of people (can't speak for the entirety but I can speak for the majority), is for it to go fast and effectively, plowing through enemies and storming through levels like it's nothing, so you can feel proud of your party's effectiveness and know that you're collectively doing well. Even that may not be fun if your party members are annoying (annoying people who play well perhaps, but annoying all the same).
Most people do not, surprisingly enough, find exp an enjoyable process if it's teeth-grindingly bad, getting 1k-2k per hour (or less) with a stupid party setup and/or fighting the wrong mobs. (Unless you're doing it with friends, in which case you're not so much having fun *exping* as you are having fun with your friends and laughing at your own incompetence.)
The fun difference between a good exp party and a bad exp party is *huge*. When 5 people want their proven effective exp setups and 1 person wants to "try something" ... consider that the innovative person's idea of "fun experimentation" may make the other 5 people want to tear their hair out in frustration. (On the other hand, they may come up with the next best thing since melee cannons. But this is *highly* unlikely.)
When partying, remember it's not just your own definition of fun that you have to account for. Which is why anyone who makes the "I'll play how I want, regardless of its impact on others, because it's my $13/month" argument is a fool unless they do everything in this game solo.
