You seem to be missing the point Kom or you just misunderstood. I have some main points to raise from my suggestion. First would be self sufficiency. If anything, people need to learn how to get shit done on their own , not lobby spam to get people to join. Solo quests make it easier for people to achieve on their own. When you say quests are meant to be done as a team , you can solo pretty much every quest with the exception being RoW , DMD , and perhaps ROCT. You would be surprised what people could do in solo mode. Most notably is TA.(You could YouTube solo TA videos for better reference.) Proof that very little quests require team play for completion. Another thing you are not considering is player skill. I face palm when I get a RA tech abusing fo in my runs causing unneeded DMC. The irony is that with players like that , it would take longer in multi than you would solo at least more than half the time. Not a lot of players here got speed running skills or proper playing. Aside from that , there is a subliminal difference in enemy stats solo-multi mode from vhard to normal. If people wanted to level , they would go to crack mode and do as they please , but when they reach Ultimate , shit hits the fan due to low level and insufficient gear. This means solo mode should be utilized mainly in Ultimate. There are other quests aside from TTF and RT. Those two quests in terms of difficulty are a complete joke. I'm talking more varied quests such as the max attack series. The quests require more skill to complete in a short time frame and some classes are not actually able to complete it in multi mode alone. PTS and DMD are extremely difficult quests when your soloing. Even with endgame gear , it isn't as easy as you think. Good gear and level does not mean easy questing, there is a ability factor. People are not just gonna suddenly join the solo bandwagon and forget team play all together. You could probably lump solo'ers into a player demographic here , with them being the minority and the minority can not affect the majority in any form. tldr , there will always be people who want to play with others but for those who prefer to go lone wolf , why not give them the environment to do so? Little something for everyone no?
P.S- I wrote this in a rush so tread lightly and take with a grain of salt