I'll make a few points:
1. METH. Gangs love it, cops love it. It's a fast way to make money, be it by selling OR seizing. And now that banks and gangs have money cap, there really is no reason not to add it back. It will bring both gangs and cops to the server. If it needs to be nerfed, simply make gathering/processing take longer.
HOWEVER. It's also true that with meth available the server also becomes an aids-hive of Altis players coming there to pull a bunch of hemmits and make a quick buck. So in reality, it depends on Statistics, and whether 90% of the server is doing flawless meth runs instead of actually playing.
2. ALCOHOL. Berry bushes grow all around Stratis. Assuming the berries are in the grape family, they can be fermented and aged into wine...a fairly weak beverage...which can then be distilled into brandy! It'd be a great S5-Exclusive.
3. The population: Honestly, my favorite pattern is a fluctuating server population. There are moments when the server is nearly empty(good for mong gangs ghost-capping turfs), and nearly-full(Agia is complete anarchy, drug fields are full, cops are lethaling. It's wasteland but better) and anything in-between works as well. Most of the time the server is less than %30 gangs and more randoms, and the island is tiny, so you're more likely to run into people.
Stratis can be both a tightly-knit community and an RDM-hellhole. I play both as civ and cop there, and I love it, and I'm sure there are many others who enjoy playing 5 for the same reasons as me.
(in the evenings and on weekends the server is usually 15-40 people, which is pretty damn good considering that we have a fraction of the landmass to cover)