I'm a casual player. and in response to that quote my belief is and has always been that a well structured game should tailor for everyone. All players should have the means to get everything at some point. Play time should never be a deciding factor on rewards. (within reason at least)
What I do sometimes wonder though is am I the only guy that considers himself casual and wants rock solid content. Seriously come on, easy mode is not fun. Now lets go back to the quote above for a second and lets hypothesise for a little about Crystal Tower. I'm going to rip off Nyzul Isle and say it has 100 floors and for every floor you climb you reach a check point. So next time you go in you can start at that floor if you reached the check point. No problem. Now even if I only play an hour a day and as such it may take me a full week of trying to clear just 1 floor I have no problem at all with that. You're group of more hardcore people with more time on there hands could perhaps burn 1 or 2 floors a day maybe even more if they're super skilled, but the point is that it would be structured in such a way that it is possible for everyone to reach floor 100 eventually.
It doesn't mean the content has to be easy each and every floor could be a challenge in itself. Floor 1 could be Darkhold. Floor 2 Aurum Vale. Floor 3 Cutters' Cry etc... (Not the actual dungeons but an example of floor structure) Most of those aren't particularly difficult but if you think back to the beginning of those dungeons where people didn't know what they were doing they were quite tricky to clear.. 100 floors of that I'd be quite happy even if it took me a week to work out the strategy for each individual floor. If it's something I could just run in and find myself sitting on floor 8-10 that same evening I'd honestly be thinking WTF.....
Perhaps I'm an idiot then. I do believe that content should be accessible to everyone in some form. I believe skill should be the measuring stick not the number of hours in your day. While admittedly there comes a limit where you need at least a minimum amount of time each day I think something akin to my example above is a fairly solid system for everyone.
It's something 11 did really well. and as much as I hate comparisons between the two when you look at systems like Limbus Einherjar and Salvage even the ZNM system. They were accessible to everyone. You could take a group of people and clear a lot of those Limbus zones in an hour or so with just 5 or 6 people. If you had a bigger group of people you could work on 2 or 3 zones at once and form up your big group one weekend to take down Ultima/Omega. Einherjar was similar 30 minutes no time extensions. Accessible to everyone. You needed a fair level of skill/gear to clear the wings in the time limit sometimes but it was accessible at least.
ZNM again could farm zeni anytime at all randomly pull a couple of friends and work through a lot of the lower tiered stuff and maybe organise bigger t3/t4s for a weekend or something.
So yeah my view is content should be accessible to all but in no way easy moded. If you clear crystal tower in a month and get a shiny piece of armour congrats, if I clear it 6 months later and get the same piece, that should never mean the content was made easier...
I'm casual and I want lots of challenges. Challenges give me a reason to better myself. Both in solo and in group content. Lose a boss fight or some content and think ok how can I improve my performance. Better gear maybe? Different skill rotation? or maybe use different sub skills? All questions that help me become better at my jobs. If things are easy then I'll never improve.
I've been called a great Paladin many times. can tank alot of stuff with relative ease but every single time I tanked Chimera I'd kick myself because even if we won I never quite felt good enough at it even if the party say I did well. Always looking for ways to up my game, thats why I like challenges. overcoming this challenge may teach me something I can take to this challenge and make it a little easier. and so on..