I think there is a conundrum in 30k around Armoured Ceramite and Melta weaponry. It also connects to game theory very nicely. Let me explain.
In 30k, Armoured Ceramite is a reasonably common and very available upgrade to vehicles in legion (and other armies, such as the Solar Auxilia) armoury. In brief, it negates the special melta weapon rules that provide an extra die for amour penetration.
Let's see if I can explain this using a logical chain.
(i) Because Armoured Ceramite is available, players are going to take it to negate against melta weapons.
(ii) Because players are taking Armoured Ceramite, it logically follows that players will respond by not bothering with melta weaponry. They'll take something like lascannons to deal with heavy AV armour instead.
(iii) Because players are no longer bothering with melta weapons, it logically follows that players do not need to invest the points sink in Armoured Ceramite.
(iv) Because players are not purchasing Armoured Ceramite, one should take melta weaponry to exploit them.
And therein is the conundrum, the contradiction, and (if nothing else) a downright paradox!
In some games that I've played, its clear that the meta is somewhere in the region of step (i) or step (ii). Armoured Ceramite is very popular (and probably rightly so). And this is leading to a decrease of melta weaponry in accord. I've not heard anyone reach the logical step of (iii) just yet, but it does follow quite naturally. I just don't think folks are thinking that far along the logic chain to be honest. And that's completely understandable if everyone is still salivating over Armoured Ceramite's ability.
But, being slightly twisted, and playing the Alpha Legion in 30k, I'm totally taking melta weaponry in the form of a melta support squad. Because my Alpha Legion force is rightly already at step (iv)!
Or at least that's what I keep telling myself. The reality is far removed from this, naturally, as most folks are still at step (i). But I will keep on taking the melta just to exploit folks who are not taking the Armoured Ceramite. That, and I think that melta guns are very powerful weapons if you're able to get in range of an enemy, and can cause significant damage to even terminator squads with the right positioning (which I plan on achieving with Armillus Dynat's warlord trait).