It is interesting that you say "it forced some people into smaller cars to tow a heavy caravan/trailer"
Here in Luxembourg, the rule is VERY simply... if you don't have the E license, your are permitted to drive your vehicle + trailer up to 750Kg. If you want to tow MORE than 750Kg, then you need the E license.
In theory, the E license does not push people in to smaller vehicles, as there is still a limitation on what the vehicle is permitted (by the manufacturer) to tow safely.
It simply means that, for example, if someone has a D3 (MAM 2700Kg). This would permit that person to tow 800Kg trailer even though the D3 is permitted to tow 3.5Tonnes. If they want to tow more, then they would have to do the E license.
If they needed to tow more, they could reduce the weight of the tow vehicle... for example:
Discovery Sport has a MAM of €2450, so a driver would in THEORY be permitted to tow 1050Kg without having the E License. Note: The DS is permitted to tow 1800Kg.
So... in my opinion, the E license has not really "pushed" anyone in to a smaller vehicle or if it has, it has not caused any safety issues, but it HAS meant that a driver that has only ever driven a Ford Fiesta for their whole life, is not able to go out and purchase a Dodge RAM, and shove a 3500Kg Caravan behind it, and then rush off to the lake district with it, try to get round turns that they cannot navigate, and then be surprised when they cannot manage.
Drivers honestly SHOULD have training before they are let out on the roads with larger trailers.
My opinion is that it doesn't necessarily have to be a "license", but SOMETHING should be passed to ensure that a driver is capable of handling what they are driving.
I would not want to go out a jump in to a Semi and start driving that down the motorway. I am sure that I know HOW to drive it, but I don't have the license.
The same goes that I would not want to drive a coach with 80 passengers in it...
I have horses at home, and I often have to use my D5 for towing. That is the MAIN reason why I have had Land Rover vehicles (D2, D3, D5, RRS, FFRR) because I want to make sure that I am towing WELL within the limit of the vehicle. AND... I did my E license when I was 20, and so I know that LEGALLY I am permitted to tow everything up to 3.5 Tonnes, and that I have had the necessary training to know how to do it. The rest comes from experience.
Having said that... there are people that have been towing for 20 years, know EXACTLY what they are doing, but don't have the E license. Even though they are not LEGAL, I will not say that they should be BANNED, but I DO think that they should have some form of "test" to show that they are capable.
For example... would you want an unqualified person to teach your kids in school, or run you country (Oh... sorry... that is already the case!!)
Please don't grill me for these comments... They are only MY opinion and everyone is entitled to their own opinions.