Well the thing is other people are also paying players. You're welcome to do whatever content you want on whatever job you want - but you can't force other people to do it with you. I wish SE would balance content and jobs better to make all jobs useful, but until they do, you're stuck either soloing, playing with likeminded friends, or playing a job that strangers/less close friends need for content.
I love BST and BLU for example... but I have come to accept that no one will almost ever want me on BST, and people will only want me on BLU for niche things. That is just the way it goes sometimes. Until delve came out no one almost ever wanted my BRD either. Now it is almost an auto-invite. That's the way things go.
You don't need to level any other jobs - but you can't expect other people to invite you on those jobs to events where they aren't considered optimal. If you don't want to level other jobs, then make friends with people who aren't so concerned about being optimal and make it work. Or, solo whatever you want. Or, start a shout group and hope people don't disband when they see what you're taking to said event.
Other people also don't have a lot of time (I work fulltime to more than fulltime, have a girlfriend, like playing other videogames besides XI and I have other hobbies such as reading books, writing and making art for example) - so that is why they want to use optimal or close to optimal strategies. Cause just like you don't feel like you have the time to level another job, they don't feel like they have the time to do multiple NNI only getting to floor 60, or plasm farming parties only getting 3K per 45 minutes, or NM battles that fail
Edited, Jun 25th 2013 11:47am by Olorinus