Whilst I agree, I can't help but point out the real problem.
This game is old.
Any productive and motivated GTA3 fan has since moved on to more modern, better looking and featureful games.
GTA3 is boring and looks like crap and yes, having interesting game modes would help but the real problem is that there isn't anyone around to maintain a healthy community.
A healthy community would be formed mainly of regular players who create clans, events, and publicity through being a player.
There would be a few scripters, bug fixes and updates, but the fact that there are players would be more than enough to maintain the community. (Eg. VC:MP)
LU has impressive lists of fixes and feature updates for every small update which happens monthly.
The script releases are advanced for the age of the mod due to great scripting support.
What we have here is a few people trying the game and leaving,
and not enough credit which the devs, scripters and players can provide to each other.
When a script is released, or a question is asked, no one responds nor gives it a go.
Some 'smart-talk'ing guys like yourself and I throw in a comment here and there thinking it improves the situation but it really doesn't.
Solution? Do and do not dictate what should be done.
Invite your friends to a LU shoot-out,
try out some scripting,
Spread the word via social media
etc
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Also,
"Set up for advanced scripters"?
Have you even made an attempt to try the available stuff out?
Most scripts being released here have a clear set up documentation including installation instructions and descriptions of the scripts.
I have rarely seen other mods have such a way of releasing scripts
The wiki is clear and is written in good and understandable English..
The language is easy and there are several examples you can look through.