This very trivial or a gimmicky things for me, if by mean "interaction" it just the NPC programmed to turn their worldy sprites towards you when your character pass near them. While in the end, when you press A to them all their reply it just the same dull, boring topics about Pokemon or how awesome Pokemon is (seriously, 80% NPC conversations are this).
I always think that Pokemon lack in this NPC department as a (classic) RPG. The last improvement we saw is how they quite improved Gym Leaders role in the story. But even that was not enough. I hope for mixture from BW's relevant role and HGSS's side story in generation 6 for the Gym Leaders (and if possibly, Champion and Elite Four or even other NPCs as well). It always nice to see their personality, not just to see them get their ass kicked or wait from other media like anime or manga to get glimpse of their personality.
If this interaction is just simple programming to make NPCs turn their body when we past near them, it just dull thing that would easily forget by other features. Sugimori Ken does a really good job at designing characters, which frustate me even moreso because they lack anything mentionable despite their fancy suit and style. Pokemon should have more named NPC outside gym leaders, and trainers.
This is a Pokemon game yes, but we play or fight with them through trainers/people in game. These people are the one who make the same species of a Pokemon feels different. If these people really don't matter that much, why would not create battle stadium instead?