It was allowed and no server owner since 2009 disallowed it, especially not now that I own the servers the past 1-2 years. (They wouldn't get kicked or banned for it, at some point Triple X did it for a little while on my servers but I pretty much told him to take the kicking effect off, so it was used to detect but after a while it got annoying for spamming ur console so it was completely removed)
Thing is HL1 allows it, it's not something you can be vac banned for and thus not considered cheating. It's "lame" but to go so far as to flame and disallow it is over the border imo.
As I previously stated, because scripters make up a hefty portion of the population (where the population is like 20 people; big whoop), it isn't an issue. But if there were a resurgence in the community before 1.3 came out, and certainly after, scripting would again no longer be allowed on the US side. Why? Because while you owning 1 or 2 servers is great when almost no one plays the game, thus giving you a monopoly on the enforcement of rules, an influx of older players would undoubtedly set the standards for all future matches and would probably own most of the servers, as well. I think you'll find most of the older players dislike the idea of giving themselves the kind of advantage found in scripting.
I'm not sure what stating VAC won't ban you for scripting has to do with anything, as HL and ESF are completely different games with completely different game play mechanics, and thus completely different rule set.
What scripting boils down to is a difference in player philosophy. On the one hand, you have people willing to win by any means necessary. It doesn't matter how you win, so long as you do. On the other, you have people who want to win with a sense of honor and fair play intact. This is why the US side created rules to prevent the use of exploits, and why you can't just juggle someone against the ceiling until they're dead. The US servers embodied the latter philosophy, while the EU servers embodied the former. As Hyb, said, its because EU players tend to be, I guess, more competitive. Not exactly my thoughts on the matter, but its probably best to keep how I really feel to myself.
You mention the initial difficulty in scripting. Hyb covered that. By changing the way you do anything, you're forced to adapt to something new. In other words, you're learning to walk again. But because you've previously learned to run, the progression is easier and faster this time around. Whatever initial downsides there are to scripting are alleviated with time and experience. I know this first-hand, because when Jinx decided to find every which way to cheat in the game, I made sure I learned what he had to offer and tried it for myself to make it easier to detect it in others, preventing false accusations in the future. When 1.2 first came out, aimbot was a factor. I remember suspecting, but never really knowing if people were using it. Eventually, I convinced evilchimp to give it to me, and I learned what to look for in others via spectating. These were big enough issues to me that I devoted time to learning all that I could about them, and how to detect and mitigate them.
These were huge issues in the past. Because it was viewed as cheating. The team went so far as to try to cripple teleportation, because the team viewed it as a threat to their system. Now, the few guys who still play, most of whom script, may not view it as an issue, but that's because they play the game in an echo chamber. ESF is no longer competitive. It's a circle jerk.
All of that said, I really don't care. The ingame community died long ago, as did the forum community. The few people still around refuse to acknowledge that, and look to brighter horizons, but nothing short of a new release is going to reverse what happened, and even then, unless proper measures are kept to retain players, its bound to happen all over again.