The hardware units are still being made and are still being lusted after by many, indeed i have several nice hardware units myself including a Neve 8801, UA6176, SSL Alpha channel and others, i, like other buyers bought them for their specific sound and control sets. All of them dictate, to a certain extent, work-flow etc and all of them have their own unique sound and limitations and THAT is why i, and many others, purchased them in the first place.
I do have plugin versions of some of them, some of them get closer to the hardware than others, but the whole point of creating a plugin version of something like the Trident is to, of course, emulate these limitations, sound and work-flow.
The Trident IS a very odd beast with its fixed frequency selections, which may or may not appear at first glance to be particularly flexible, the trick with it is to realise that all the bands and filters interact with each other and it takes time to familiarise oneself with them, i don't claim to be too familiar with the original hardware as i've only used a Trident desk on one occasion, but from what i remember and from the opinions of many other people who ARE more familiar with the hardware that this is the case.
If EVERY EQ on the market had essentially the same control set, things would get very bland very quickly.
As with any piece of hardware it takes time and effort to become fully cognisant and familiar with what you personally like and dislike using it for.
The guitarists i know that use this, or other versions of the Trident, and myself all treat this as a 'character' EQ, get as close as we can with the plugin's controls and, if needed, follow it with a more transparent EQ.
If you spend more time with it you'll come to realise this, again, this is why things like the 1073 are SO popular with the rock and jazz crowds, despite its minimal feature set, and AMS Neve certainly have no plans on changing this.