Formations aren't removed or useless, the Homeworld 1 formations are simply bugged. As ships leave them as soon as combat starts, as you said. Let's hope they simply fix the bugs.
Evasive tactics was lost, but to be honest, the Homeworld 2 interface brings a lot more to the table otherwise. It's way easier to launch all ships individual special abilities now for example.
The biggest, HUGE deal for me, is that ships in Homeworld 1 ALL die far, FAR faster than in the original. Not just strikecraft as the review suggested.
In the original, your destroyers and frigates could be firing at one another for several minutes before the really big ships got destroyed. Now, whenever you've got a few destroyers in place, frigates die in mere seconds and even super-capitals that get focused are blasted super-fast.
On the flip side, though fighters die faster as well, they're actually far more useful against capital ships now.
I simply don't get why a company would go through all that effort to upgrade the graphics in a massive and beautiful way, only for you to be unable to enjoy those uber detailed ships firing their guns for long, as they get blown up in seconds.
Apparently they did it to bring HW1 ships into multiplayer together with the HW2 ones. A very bad decision, they have no bussiness being there together.