The EVA isn't causing leaking but it does act as a sponge and it holds the water next to the boot,plus its about as cheap of construction as you can get.Combine that with a proprietary membrane of unknown make up and it's little wonder they leak.Your pair of 1 1/2 year old leaking chink made vasques isn't much of a testament,but I do have a pair of chink vasque velocity goretex tennis shoes that are three years old and have about $60 worth of loctite super glue holding them together.Still waterproof even with standing water in a boat.
I've had single vamp lowas and they weren't a single bit better then other lowas,which means they were all waterproof and I wore out the boot before leaking ever became an issue.I've got a pair of Lowa Tibets right now that are 4 years old beat to hell and get worn year round that are still waterproof. The rand has yet to tear or seperate which does a bunch to prevent leaking.
Gore tex in a sock construction like danner uses is arguably the most waterproof design,I've had danners where the toe box was ripped wide open and the goretex membrane exposed and still the boots were not leaking.Plus there isn't a part on a pair of american made danners that danner won't or can't rebuild.
Kenetrek is a comfortable boot,which in itself is a major selling point,but their construction leaves a lot to be desired.
If your wearing out a pair of boots in a couple seasons it could mean you're actually hunting.