I think you can level by slaughtering monsters. It's not fast, but it should be noted that you should always feel like you want to group since that is the way to progress the fastest. If you feel like soloing is "just fine", the incentive to group is just not there. Especially for us, who live in the Western individualized societies where we'd rather stick to ourselves or hang in our own little communities. We interact when we have a good enough incentive to do so.The problem with the above is that apart from Behest, the above is the only way to level provided you can find somebody who has leves on them. You should be able to go and level and do so all day if you wish. Being restricted causes people to get bored and log off.
However, while slaughtering monsters already works, they could indeed make a system designed for soloers to get SP that doesn't come close to that of group leveling but is better than not doing anything at all. It's something to do while LFPing for leves. Hamlet defense battles could have worked like this, but I don't know what the current plans are. The leve system and related features like search can be further improved still though.
So you would essentially want to do more work for same gain? They can keep the current cooldown and the system will work with few adjustments, so why make yourself work more for the sake of this 'freedom'?If SE control how fast we level maybe they need to change that as well.
All these games control the pace at which you gain levels. They could simply make it so you can gain 4h worth of exp from two quests and then put a limitation on it so you can't do more till the next day. It's all the same, designed with the majority playing X time per day, and adjusting rewards according to that. This system works better for those with little to no time, as you can get more done in a smaller timeframe, while those with more time can still play with others who have leves and progress further. There is simply no mutual interest for groups and those looking for group to team up nor a proper way to recruit and be recruited right now.In FFXI or any other MMO I have played, I can logon, EXP for 3-4 hours with your equipment/stats/skill increasing the speed in which I gain the EXP, go do some content, go back 1-2 hours later and continue..