I don't know about you, but most people have jobs, obligations, families, hobbies, sports, generally called a life outside this automated grind game. Other than that, there is no situation outside pvp (and maybe some end-game content), but none whatsoever, where playing manually outperforms a macro. Active play is gone, since those long gone days you mention, things have changed and we are playing a different game, either we like it or not. It is not possible, effective or even sane to play activelly in a farming party. What do you expect, people to set up a party, turn on the macro and then sit in front of the monitor and stare at it in order to have your active play? That can't be right in any scenario you can think of, for any normal person... Do you need to communicate with people, are you looking for socializing? There are far better options than the l2 chat, trust me...
Regarding the party matching, is it emptier now than before the raise of the limit? Obviously not, and it will stay the same even with 1 client limit. And the reasons for that are quite simple for anybody who uses half of brain: first one, for the reasons above it is not efficient, and secondly, you depend on other people in a party, and that is not a situation you can control. People get d/c, leave without announcing or you simply can't find replacement, and you end up spending more time trying to put the party together than actually playing, or even more. Is this right? Maybe not, but you need to farm 24/7 in order to get anywhere in this game, and that simply can't be done the way you want it.
Since you mention nothing of the other aspects of the game that require multiple clients (I imagine they are of no interest to you, but quite necessary for the game), may I suggest as a solution to your discontent finding a constant party?
People generally don't need more than 3 chars in order to avoid actively looking for parties, and people who what to play more, simply get a cheap machine to run them, it's not the 3 client limit that stops them.
Any way you look at it, the client limit does not influence active gameplay or party forming, and does not affect people who want to play by themselfs. What you ask for will not get you what you want, and simple evidence is that the situation was not different when the 3 client limit was in force.