I think they need to do a better job making sure people parking in the lot belong there. We were there for Food & Wine in Oct 2 years ago. We came back one night around 7:30 couldn't find a spot in the main lot, we had to park across the street. A few night later we came back at 9:30. There was a mass exodus from the main lot. We were able to get a spot in the first row of the main lot.
I'm sure these weren't resort guest going out for the night.
for the past few years, access to the main resort lot (the one across from the convention ctr) has been more strictly enforced.
we go every year: 10-12 days during the F&GF, and again during the F&WF (and sometimes another trip in august
).
during peak times (F&GF fri-sun, and F&WF just about any time EPCOT is open), there has been a guard stationed at the lot entrance (across from the convention ctr) checking BWI/BWV guest parking passes, often asking for matching photo ID.
at the guard shack, they usually instruct non-BWI/BWV guests to park in the lot across the street, else use valet (since they put up poles at the lot's first entrance & a guard at the second, ppl can't sneak in any longer
).
however, if there is a convention or special event, they will open that lot to ppl attending. i heard there was a problem with that lot being filled with convention goers a few years back - perhaps you had gone during that time. personally, i would find parking across the street from a resort i was staying at totally unacceptable - i would've asked for either a spot in the left side lot (behind valet) or comped valet.
we haven't had any problems whatsoever finding parking spots near the front since they started restricting lot access
Changed from AOA suite, to Poly, to now BWI. Couldn't be happier.... just waiting for discounts to cut down cost! 
