That's still a starbase, upgrade, and required research you need to invest in to keep your worlds safe. And you need to place one at each planet. Meanwhile, you just need one Novalith to keep all of your enemy's worlds at risk. And, on top of that, a Novalith angled at a planet means that world isn't generating any tax income ever again.
That's besides the fact that the TEC don't even need to invest in a fleet for their weapon to work at its full potential. You just build one, turn it on autocast, and watch the fireworks. Or, if you're feeling mean, find a terran planet and check back every so often to make sure your Novalith's constantly firing on it.
So, in my opinion, the Novalith is just fine. It plays into the TEC's style like the other superweapons play into the other race's; it helps the player maintain economic dominance, just like the Deliverance maintains cultural dominance and the Kostura maintains superior maneuverability. Damaging planets is just a plus, like the Advent's damage bonus (I've never played Advent, so correct me if I'm wrong) and the damage the Kostura does to orbiting ships.
And it still makes one of the biggest and prettiest explosions in the game. 
