Other languages are resource-intensive, not in the ordinary CPU/RAM/disk space/bandwidth sense, but in the human resources sense. Everything is always the host's fault (even, unfortunately, when proven otherwise), and supporting alternate languages means having support people who are familiar enough with the language and the surrounding config to allow people who are willing to accept bandaging to fix their own self-inflicted foot wounds. It's also quite normal for people to expect that the wide-open environments on their local dev machines will be reflected on the server, where the possibility of tromping all over everybody else's work is all too real. That is particularly true on Free Hosting, where there is essentially no incentive beyond basic decency (something altogether too lacking these days) to play nice with the other kids in the sandbox.
The free hosting space is not intended for anything much more intensive than hobbyist/personal use. There are a variety of low-cost options available for anything that needs to be in any way mission-critical, or that would require more domains, or that need language environments not part of the usual XAMP stack (many of which cannot run without having a permanently "up" core process due to delegation, callbacks and promises, which means that you need at least a virtual machine with a minimum of full-time space for your account).
Much of the negativity comes from two sources: unreasonable expectations of what a free service ought to provide (like people can get "ripped off" somehow when they're not out of pocket at all); and users who've broken the Terms of Service and had their accounts terminated because of it.
Concerning the first, the servers are provisoned based on the usage expected for Free Hosting, so there are occasional times when the load is greater than expected -- pages may be slow to load, requests may time out, and the outbound mail queue may be flooded without any one single user causing all of the problems. Sometimes abusive accounts (or poorly-coded ones) can consume a lot of resources deliberately or accidentally. Occasionally user accounts will cause entire servers to be blocked by ISPs and mail providers, and it takes a great deal of work to iron out those problems when they do arise. And while I can understand people getting frustrated when bad things happen to their sites that are not their fault, it's the nature of the beast. Free services are always risky because there is rarely a down side to abusing them, and the abusers take everyone else with them. And some folks have just plain failed to notice the big sign saying that the space is being provided for websites only, thinking (apparently) that they've found a free cloud storage solution. (I'll admit that "unmetered space" looks tempting compared to the paltry few gigs that folks like Dropbox provide on the free tier.)
As for the second, well, there are people who simply don't understand that IP laws are laws and not merely suggestions and guidelines, and that even if they aren't Americans, x10Hosting is American, is required to meet American law, and may be liable in part for what its users are up to. Since there is nothing substantial tying a user to an account (remember, it's a free service so there cannot, by definition, be a contract), the host is a large and obvious target for damages, etc. The usual defence is either "personal use" (doesn't matter) or "fair use" (indicating a complete inability to read and understand the laws concerning fair use or fair dealing; tagging entire movies, albums and software cracks "for educational purposes" doesn't begin to meet the provisions).
All in all, x10Hosting is pretty up-front about what they're providing and what they're not providing as a free service. Whether or not that meets people's expectations of what a free service should be is an entirely different question. I happen to think that you get an awful lot for a twenty-second-a-month login cost; others may feel hard done by.
