Despite having completed several basic and intermediate level handgun courses from certified instructors, I still had to take the State required 12-hour Concealed Weapons Course in Michigan before getting a permit. I found it was a good idea, not because I learned anything, but I was very glad some of my classmates had to take the course. IMO, 12 hours is probably not enough for some people. We could have filled another four hours with 'need-to-know' content, because there were people who needed to know it.
As far as Texas goes, there is no reason nor logic to support the idea that these individuals would not have committed these crimes had they not had a permit. Plenty of non-permit holders out there carrying guns and committing crimes, they seem to do pretty well without the benefit of a CHL.
Many of the firearm offenses reported do not involve the firearm permitted to be carried, but instead are violations of hunting regulations (not relevant to CHL), or are otherwise technical violations such as accidentally (often unwittingly) carrying the firearm into some prohibited area, and do not involve any act of violence or even any threat of violence.
Still others are 'crimes' of indiscretion; failing to keep the firearm completely concealed at all times. If you bend over to pick up a quarter, or getting out of your vehicle at the supermarket, and your shirt/coat temporarily rides-up exposing the firearm, some hoplophobic soccer mom who happens to catch a glimpse of the gun is probably going to become hysterical and report a 'crazy man waving a handgun around threatening to shoot the children' to 911. If the police have to respond to such a report, even if the caller grossly misinterpreted the situation, you're going to be cited for your lack of discretion.
One of the [IIRC, there have been two convictions to date] Texas CHL holders convicted of murder was charged resulting from a fatal shooting which occurred in his own home during a party. The permitted handgun was not the firearm used in the shooting.
As we all know, no state in the US requires a CHL to own and keep firearms in one's home, so this conviction is irrelevant to the fact he was a CHL holder. The man's possession of a CHL did not 'enable' or 'facilitate' the shooting in any way.