Most guilds are currently running 3 hours, not 4. Still, I completely understand that for some people it is just the fact that they must be on at that time that makes them unable to do it. However, it is no different than say a bowling league or pool league. The team has to have set times to meet that everyone agrees to. You may say well bowling and pool only play once a week. Well that's true, but they also meet 1-2 other nights a week for practice. Also, it is not really a time commitment once you reach a certain point. The only thing it requires outside of raiding is making sure you either can farm mats for, make your own or buy a few raiding consumables. Some guilds even help with this. Really though, all you need is a few Vials and couple Whetstones, at least for melee, not sure what casters use for weapon buffs. It amounts to 20plat or so a raid night, if that. You also need to make sure you can afford to rune your upgrades, though again, guilds are usually very helpful with that. What a lot of guilds I have been in do is just throw your BoE gear in the bank, or there is a specific person to send it to. If everyone does this, there are tons of mats then they rune stuff for free.
Is it more difficult? Yes.
Does it require more time? Yes. An Expert takes 30-45 minutes in a well oiled group. Clearing TotDQ can take an hour even with a well oiled group. That is more time, about double really. FT takes maybe a little longer but once your raid group is geared and knows what to do not really. It's not so much that raiding takes more time, though it does, it requires more attention and coordination though. One person can wipe the whole group fairly easily on a lot of encounters, and that is what makes it "harder" not the amount of time it takes.
Personally, the difficulty for me lies in the fact that I still have rep grinding and other things to do on top of raiding. I still need to grind GHunts, CQ, Keepers, Caretakers and Qaijiri rep. I raid 3 nights a week, 9 hours. That's near my limit already, so the farming on top of that is what brings me up to 20 hours a week. Though the past couple weeks I have not been doing anything other than maybe dailies.