One of the great things about 102 Ave in terms of walking is it's quiet - it's easy to have a conversation while walking and the atmosphere is pleasant. That's why I mostly avoid Jasper Ave as a pedestrian and obviously on bike, it's not friendly to anything but cars and my experience as a pedestrian is poor.
Absolutely. There's a reason that 102 Ave and the Victoria Promenade have way more pedestrians than 104 Ave and Jasper Ave, despite the latter 2 having a lot more things to gravitate towards. It's also a stark contrast to Westmount, Alberta Ave, McCauley, Strathcona, and (sort of) Garneau, where the main street is the busiest for people (but also because they're safer and more desirable). 102 Ave seems to slowly be turning into a more Downtown-y version of 76 Ave in Ritchie, which I'm definitely not against.
An interesting point comparing Jasper Ave with all its potential retail space (much of which has been around a long time) to here where it is being recently developed. I agree the quieter area off the main street has a more pleasant atmosphere.
Jasper Ave is a busy main street and will probably remain so, but it would be nice to try make it more pleasant too.
I don't think it's that Jasper Ave is a busy main street. Ste-Catherine, 5th Avenue, Michigan Ave, Oxford St, the Champs-Elysees, Ku'Damm, etc are also busy and bustling, but it doesn't prevent them from being well-regarded destinations. In fact, the busy-ness is indicative of their attractiveness. The difference is these main streets are oriented more towards the pedestrian experience, whereas Jasper Ave (particularly outside Downtown proper) is not - it's a stroad, which is why it's unpleasant and undesirable, because it's unsafe.
That's not to say quieter commercial/community areas are bad, either, or to counter your claim that they offer a "more pleasant atmosphere" because, in the case of Oliver, that's pretty obvious. One of the most interesting urban neighbourhoods in Western Canada - Winnipeg's Wolseley is also very quaint and charming in this way, with a small, popular but not overwhelming main street nestled in thick elm canopies and colourful Four Squares. But I think busy main streets can also be pleasant, it just depends on how they derive their busy-ness. Obviously Shibuya Crossing isn't for everybody, but it's popular for a reason and the reason isn't cars. Ultimately, I'd love to have a vibrant, walkable West Jasper to complement 102 Ave and 100 Ave's more quaint aesthetic.