I don't see how environmentalism or for that matter meditation itself is creepy.

Which goes to show how far into the zeitgeist they've penetrated. Go back to the 1960s when the cult panic and popular image of cults was being set, and things were quite different. One of the papers discusses a major lawsuit accusing the Hare Krishnas of 'brainwashing' a teen girl when she ran away from home and stayed with some Krishnas; the precipitating event was her parents getting angry about her meditating in front of a little shrine, and ripping it out and burning it (and then chaining her to the toilet for a while). To people back then, 'tune in, turn on, drop out' sounds less like a life choice than a threat...

What's creepy about Hare Krishnas is the zoned out sleep deprived look on the faces (edit: I am speaking of the local ones, from experience)

Well, I can hardly argue against your anecdotal experiences.

the whole obsession with the writings of the leader thing,

Supreme Court - jurists or cultists? Film at 11. We report, you decide.

and weirdly specific rituals.

I don't even know what 'weirdly specific' would mean. Rituals are generally followed in precise detail, right down to the exact repetitive wording and special garments like Mormon underpants; that's pretty much what distinguishes rituals from normal activities. Accepting Eucharist at mass? Ritual. Filling out a form at the DMV? Not ritual.

You can go to a local Yoga class, that manages to have same number of people attending as the local Khrishna hangout, despite not trying nearly as hard to find new recruits.

Hmm, where was one to find yoga back then... Ah yes, also in cults. Ashrams in particular did a lot of yoga. Interesting that you no longer have to go to an ashram or fly to India if you want to do yoga. It's almost like... these cult activities have been somehow normalized or assimilated into the mainstream...

You can join a normal environmentalist group.

And where did these environmentalist groups come from?

For example, putting up a portrait of the founder at every workplace (or perhaps in a handbook, or the like) would be something that a cult leader would do in a cult, but what a corporation would seldom ever do because doing so would be counter-productive.

Really? That seems incredibly common. Aside from the obvious examples of many (all?) government offices like post offices including portraits of their supreme leader - I mean, President - you can also go into places like Walmart and see the manager's portrait up on the wall.

What do you think makes joining a cult worse than joining a club, getting a job, and so on?

Personally? I think it's mostly competition from the bigger cults. Just like it's hard to start up a business or nonprofit.