I would disagree on "super slow" - their base speed is 7". No guns, so Advancing is a given (until you're ready to charge), so even without Kraken you can set them up to cross no-man's land by T2 pretty reliably.
That said, they're overcosted for the CC "punch" they provide - it's either lackluster compared to cheaper options, or paying a premium to be the only infantry unit capable of taking still-expensive-but-worse power fists. Although these got cheaper in the codex, not cheap enough to really run as a punchy unit on its own.
So what about the purpose that is their literal name? Meh. Still too expensive. They're less points efficient per wound for a naked tyrant, so you have to *really* deck one out before it starts to look mildly attractive... and then you have the option of paying X points for extra wounds on a 2+, or x+20 points (crass estimate) for a second Tyrant with all those goodies that you're trying to protect (read, guns and a capable combat statline, psy powers, and synapse) anyway.
They're not even super expensive models - I think about 35 points? But if we're just looking at cost, I think they need to be essentially the cost of a Warrior (24, 25 w/Adrenals) to be viable. Next to zero versatility, but really good for their cost at their job. Otherwise taking a 2nd Tyrant is always the better option. Drop a couple of genestealers to make up the points difference.
I'd prefer to see the cost not drop (or at least not that dramatically) and gain a couple of the above options (or something else) because I think that's more interesting than "cheaper to the point that it's finally worth it". Of course, FnP built in could get messy, as you can catalyst the Tyrant, take a wound, roll catalyst, then on a fail you pass it off on a 2+ and get another FnP against the MW (then again, the capability of shrugging of wounds is their entire purpose, so maybe that should just be a thing).
They don't even have the benefit of wounding T3 schlubs on a 2+ to help clear out chaff that would be holding your Tyrant back.
Alternative idea to add to the pot - Shieldwall becomes: while within 3" of a Tyrant Guard unit, a Hive Tyrant can not be targeted as if it were a character with 9 wounds or less.
Apparently "the internet" is of the mind that people get around the current Shieldwall by just "killing the Guard first" (which isn't suuuper hard to do), so this maybe wouldn't actually change things that much. But I think it would be cool, especially if combined with a 5+ FnP aura granted by the Tyrant.
Guys I want walking Tyrants to be a thing again, because they look boss. But all Tyrants look boss, so really it's a win-win anyway.
