You all seem to have put aside the fact that Wing was made about 10 years before SEED, and thus the technilogical abilities imagined were obviously going to be less for Wing. Phase Shift armor is well, i don't even know what exactly it is but I can't imagine it ever being employed in every unit. Beam weapons are cooler, agreed, and obviously the Seed gundams have better defense and niftier stuff because the creators could work off of existing Gundam models and improve them (Forbidden - off deathscythe, Buster - off Heavyarms, Duel - off Tallgeese?)

Also, remember that Gundam Wing suits were designed to destroy military instilations and took place in a world without crazy carriers and without high-fire powered motherships and whatnot like Minerva.

So just remember and think about all the time they had to go back and change the original models from Wing or wherever they're from (Goufs, Zakus, those Cancer like underwater units, Djinns of Aries)
Naturally the newly thought up suits will be able to take down ones from older series, because they were designed with the flaws and knowledge from the older ones being kept in mind.
But that is assumming the newer pilots are also better than the old ones. But of course the new ones are Coordinators and have SEEDs and all this crazy whatnot that simply could not be imagined back when Gundam Wing or anything was being made. "Kira would own Amuro because he has a SEED!" And because gene manipulation and stem cell shit was so around in the 70's...

just remember the differences in context and time period and the changes in technology between series when discussing shit like this