Backreading this (so many posts suddenly) and I think the biggest problem I have with alternate universes where the field trip was peaceful is that a peaceful field trip may not actually have the Little Busters as we had come to know them.
Let's see what we knew of the rest of the Little Busters before the field trip
- Mio and Kurugaya would barely talk with the original LB
- Komari was known by all of them but wasn't on friendly terms
- Kud was just seen as the "exotic foreign girl" and would maybe talk with them every now-and-then
- Haruka would play around with Masato and Riki because she's cool like that
So if the accident on the bus never happened, why would they suddenly be a friendly group? The only reason they got together was because of the accident. As such, I can't see how things like 4koma and Kud Wafter even being possible without an accident to have brought them closer in the first place.
Which leads to the question: "Why are they a friendly group even after the accident?" Well I believe that they are self-aware of what exactly happened in the dream world. In Bokura no Asa, Riki does not consider that as simply a dream involving his classmates, and I am sure that the people involved in the incident feel the same way. Even if, for example, they don't remember the exact details of what happened, the bonding that they shared over multiple repeated months stuck with them after the accident, thus allowing them to become closer to each other after the chaos had subsided from the accident.