I miss that too. Those kinds of sims really seem gone. When I still played often, I "sacrificed" part of my role-play time and a character, making her get a job at a tavern exactly because it's a great place and way to help new players get involved without having to IM and worry about intruding on others' scenes, and feel welcome, and get to know resident characters. Very simple, and in character, by just dropping by. It was a great opportunity also for people who can't be or don't want to be glued to their screens all day or night long to have a bit of fun and add to the sim, atmosphere and story in their own way.
It was so easy. You looked at a sim, read the info, got excited if you seemed to like the sim and had a character that fit in or a good idea for a new one. You filled out a simple note card and usually could start to play at once, for example in the tavern, before the excitement (or the sim :P) was gone. Without registering outside of SL on a website, having to spend hours on an application, figuring out how yet another HUD works after registering it on another website, only to then not find anyone there or everyone playing in cliques at some place where your character has no chance to get to in character. Or literally every single character you meet being that kind of uninviting already at first encounter that you feel as if they really want you to hit the road out of character too. I played "evil" characters too, sure, they might hate everyone, whatever. But still it's possible to play in a way that shows especially a new to the sim person that they aren't disturbing and that you have fun playing with them, even if their character might like to roast you for dinner.
The "old sims" were easy to get into and, to me, felt more creative and collaborative, and like spending free time and not like applying for a full-time position, and seem all to have closed or disappeared over time, and I gradually played less and less.
Maybe the new sims are great for new people. But where are the old people from the old sims? Did they all stop having sims and role-playing, or are they all happily having and playing on the new kinds of sims?
"Why so many empty role-play sims?" There are either too many sims or too few players, or both. There should be an official limitation of 3 sims per role-play genre and only when one of those closes, a new one may open. 😛