Not really... Sure they will be a pain, but if you got that many DE's you would kill many more of their planets (and make them burn a bunch of money trying to stop it anyways). Same concept applies to Kosturas. They don't kill planets, but they damage and disable ships and structures as well as sticking a phase node there. Shoot their well hidden worlds and jump in a guerilla force and watch them suffer. This allows you to turn any of their planets into a choke point. You don't win with superweapons. You win with fleets and since Kosturas augment your fleet's ability to take worlds as well as defend your own. For this reason, Kosturas are the best superweapon.
If you really felt like arguing the point...
Novalith: damages a planet. Upgraded ones requires two shots in order to be killed. Prevents recolonization for a short time. The value is that they lose tax income and are unable to build structures for a short while.
DE: radically increases your culture in the area in which it was targeted. This reduces the income of multiple planets and should multiple shots be chained, it can result in the loss of a cluster of planets. The value is potential loss of planets and definite reduction in allegiance and thus income from taxes and extractors.
Kostura: damages ships and structures as well as creating a phase node. This makes attacking a planet much easier and I believe will also wipe any mine field that has been discovered. They are also capable of allowing you to send a force of an egg,an antorak, some assailants, and some SF's to wipe out one of his rear worlds. Once this happens, you can take it and build your own phase gate, fully integrating it into your empire. This forces your opponents to guard every world which they cannot possibly do (unless they themselves are Vasari).
The Kostura is the best. It may be the most unusual, but its a lot easier and cheaper to put colony frigates everywhere than a fleet. Also, it gives you the opportunity and usage for your Antorak. While typically believed to be worthless, the Antorak is absolutely astounding late game as a guerilla fighter. It knocks out the ability of enemies to respond. Combine this with Overseers and they can't jump in reinforcements. Not only that, but over time, its going to level up and you just a ship that has the perfect panic button. Find yourself far behind enemy lines and doomed? Just instantly jump back to your homeworld and heal.
Its not so much about the raw income that make TEC stand out Economy wise. Its the fact they can field a few more ships per fleet upgrade, Their ships are much cheaper to replace. So losing part of you fleet in a slug fest, isnt as dangerous as it is to the Advent or Vasari. A TEC player can afford to lost ships even with a slighty worse Economy than his enemy b/c everyship is cheap.
Thats my point. Is even in a pinch, the 'better' TEC Economy is not raw income. Its more effecient use of what you have, aka ships are cheaper in just about everyway. The Hoskio main advantage is not honestly saving your ship. Its keeps your dying ships shoot that much longer. Which hopefully is enough to either kill a few more ships or a Cap of your enemies. Or even give your renforcments a few seconds longer to make it.
Thats why the term to Better Economy as the TEC main advantage is not as straightforward as many think. Or even as forward as the other races advantages.
IMHO, its really their support abilites plus cheaper ships, which really allow you to save income. Since your saving more it seems like your Economy is better. Hence is why TEC get flagged with the better economy tag. And that leads people to try and build trade ports super quick, thinking thats what a better economy means. LOL, oooorrrrrr maybe this just makes better sense in my head.
Yes they do have cheaper ships. But no race should spam TP's early. The same goes for light carriers. You just can't support them early on. After a while though, they do become useful. Until then, not so much... The real reason TEC are good is their ability to replace any ship you kill with three more. Rapid manufacturing for example. What about industrial juggernaut? Same thing. You can spam any amount of ships and not have to worry about their death. This concept of throwing money at problems is really how any rich country operates today. We throw money at problems. Now, a lot of it goes to waste, but it always does something good. This theory even extends to the Argonev and its big red button. It cost you a lot, but you can always replace it. A fleet is harder to replace though, so you blow yourself up. The TEC have the numerical advantage. They don't have the power of the advent, nor the toys of the Vasari, but they are hard to kill because they are by far the most resilient race. Kill one ship and the TEC player has three more coming your way. That is why they are so good.