An interesting idea. I often agree that its too easy to get to dreadnought tech. However, you can build these ships, but the weapons that go into them need to be updated as well. So even though you can build the dreaded DN, the weapons it cares are weak until researched out.
------------------
"We've made too many compromises already, too many retreats! They invade our space and we fall back -- they assimilate entire worlds and we fall back! Not again! The line must be drawn here -- this far, no further! And I will make them pay for what they've done!" -- Patric Stewart as Captain Picard
UCP/TCO Ship Yards