Anyone else feel like the INSANELY BIG ANCIENT EGYPSHUN LAZORZ sort of lack impact?

[Tiggy]

How it feels is entirely subjective. They feel like they hurt a lot to me, and obviously your standard is different. The visual of a gigantic laser hitting me is adequate. The fact you need further bangs and whistles makes me think you undervalue the power of lasers in their simplicity. You just want bells and whistles and I base that off this quote.

On the other hand, Akh Morn, used by a certain dreadwyrm, has impact due to the relentless succession of attacks. The duration of the attack itself is short, but it's the quick succession of them that does it in that case.

Here it's not even about the laser. You just like how it's followed up with some flashy attacks for a flashy SEQUENCE of attacks not a flashy single attack. So ultimately your complaint isn't even about the lasers. You want more intense sequences of attacks.
Let me tell you think though. Using the toughest fight in the game as a baseline for other content is generally a bad idea. Akh Morn is specifically trying to murder the crap out fo the tank with that sequence. If used in other content it would mean a lot of dead tanks because it was simply too much going out at once for more casual content. So yes, this discussion does at least in part relate to casual or hardcore content. Long damaging sequential attack patterns are going to be in tougher content and not in easier content.