Nomura shouldn't have even had Donald and Goofy meet Ven in BBS. It just doesn't make sense to me, and I know it doesn't make a lot of sense to other people. I don't like the "it was a long time ago, so they might not remember" excuse, because Mickey did and so did Yen Sid. Hell, even Riku remembered Terra.
I wonder if Nomura will clear this up in KH3, but I have a feeling he'll just ignore it.
Thoughts..?
You're comparing apples and pears here. You cannot say that just because person X remembers person Y, Person A
has to remember Person B.
It also depends on the impact of the meeting of those persons, the length of it and if the person B/Y in question is longer on Person A's/X's mind than just that one meeting.
That Yen Sid and Mickey remember Ventus is easy because despite everything else that was going on between the end of BBS and DDD, in the background they both were actively looking for his whereabouts as well as Aqua's and Terra's, so the memories of the BBS-Trio were kept fresh over the years in their minds.
Donald and Goofy had only
one encounter with Ventus that wasn't much longer than the one Ven had with Lea.
So with Donald and Goofy in regards to Ven it is the same as the memory of Lea in regards to the same person, as their meetings were not only short, but also of less personal significance than Terra's and Riku's meeting was.
The meeting between Terra and Riku held much personal value for Riku himself, so the prospect that he
may have remembered (DDD actually indicates that Riku only remembered Terra shortly before fighting Ansem SoD again) is much more logical than Donald and Goofy (or even Lea and Isa, for that manner) remembering a kid they only met for 20 minutes most in more casual circumstances. If anyone should remember Ventus clearly beside Yen Sid and Mickey they are Hercules, Stitch, Zack, Peter Pan and
maybe Phil because with them Ventus was unquestionably closer in terms of interaction than Donald and Goofy were.
Thus, the fact that they have forgotten over the course of ten years is not really an "excuse" but a reasonable explanation, not everyone possesses eidetic memory that works for over ten years.
Most people wouldn't remember the faces of people they met ten years ago, let alone Donald and Goofy. Neither Mickey nor Yen Sid ever met Roxas, nor was he ever relevant to their plans. Even the people who did know about the Ven/Roxas connection (i.e., Xigbar) didn't really say much of it.
As for Riku, strangers probably were a rare occasion for people on DI, and the whole experience must have been pretty enigmatic/fascinating for Riku. So, it's not far-fetched for him to remember Terra.
Not to mention that Terra did something really special before Riku's eyes that directly involved him, both Sora and Riku do
not remember their encounter with Aqua (until DDD at least that's when Sora recalls the memory, but we do not know about Riku) since it wasn't that much of a special occurrence as Terra's encounter with Riku.