Let me share with you my opinion largely based on LU and a bit on my VC:MP experience.
The argument posed to me by scripters was that no one cares for racing games among the community. So this is me checking to see if that's really true.
It can be true. For the many racing servers I played, the most successful ones seemingly where the ones were the playful side prevailed over the competitive side. As personally I love competitive races in GTA multiplayers few seem to take on the challenge, especially newbies give up easily when competitors are too skilled and racing alone just to get a better time soon becomes boring. That leads to my second point:
Racing servers are less prone to get one player if there's none, mostly because you can't easily freeroam in the city or do other stuff waiting for other people to join.
I think there should be a compromise between those who like competitive racing and those who prefer to mess about. To not shy away the less skilled players, for example allowing ramming (not in every race pls), a pickup system with good as well as bad ones, and other features that allow you to compensate or even take revenge on the more skilled players if you can't overtake them.
in VC:MP I played eXtreme Racing Revolution, some shortly lived racing server from Shadow and Miami Dade.
I feel like saying XRR was my favourite for the incredible amount of tracks, over 400, the short length of tracks which prevented it to become boring, and a few customising features as setting the car colours, locking the radio and setting your skin.
the one from Shadow instead was a bit more competitive, I remember that I liked it but honestly not sure why anymore. I remember it had a neat GUI and a custom track, but I didn't like that cars were given randomly from a preset list so I was overtook in a straight lane due to having a slightly slower car.
Miami Dade honestly was ok, the announcement system was causing big fps drops even if your pc was average (let's say a device that can manage an average 40-50 fps) thus disrupting races when they showed up, the tracks weren't many, often too lengthy, and the red coloured huge spheres often prevented from seeing the occasional lamp post that was just behind them. Last but not least the server often suffered crashes due to script errors, that required poking and waiting for Juppi to come to life and restart the server. As an upside I really liked the point system + online leaderboard, which can be seen here:
http://mdr.project-apollo.co.uk, then again the system they used was innovative as much as fucked up. You'd win or lose points based on some factors like final position, number of racers and total amount of owned points, etc. The fucked up part starts when you reach a relatively high amount of points, e.g you'd finish 5 races in first position and earn a total of 54 points only to lose all of them and more, because of a 2nd place right after.
That is all I hope I didn't go off topic too much.