The two things which make Dominators worthwhile are access to large ballistics, very high armor, high OP, and burn drive to get to the fight quicker than the Venture. If all you need is a tank, Venture is much more cost effective. Just fill it with tank mods and PD. The Dominator, however, can be tank or damage.
The Dominator is definitely not a tool for killing speedy targets. Which is perfectly fine. It has access to two large ballistics slots. That makes it great at taking out cruisers, capitals and slower destroyers. Aux Thrusters is still a must IMO, however. It's absolutely necessary for tracking ships with its large ballistics. As far as kinetic damage goes, IMO large kinetics aren't worth it when small and medium have such better alternatives. Only exception is Gauss for a pure sniper ship, but there's no Vanilla ship which can really optimize the cost efficiency of the Gauss to the same degree as other weapons.
Since medium is required for PD, however, you're left with using small slots for kinetic....which is perfect since small ballistic PD is terrible.
Why I like the Dominator is because it has many viable options for the large slots. Hellbore is always great for making armor evaporate and keeping flux demands down. Hephaestus is a great all-arounder, though rather expensive against well shielded targets. Devastator is a mixed bag of effectiveness, but much cheaper on the flux and with a very good PD capability. Mjolrnir is another great all-arounder, though with different areas of strength.
And it also has the lowtech benefit of high OP that I rarely see others take advantage of; it's OKAY to leave the less effective mounts empty! I nearly always leave two of the side slots empty. In fact, for my ranged damage support Dominator, I'll leave all small mounts empty so I can get a Converted Hangar, flux mods, and max vents to support 2x Gauss and 2x HVD.