I could be remembering wrong, but I recall reading somewhere that Alessa was apparently the catalyst of the otherworld's creation. I recall when Origins was released some people had a problem with it because Travis interacting the otherworld contradicted something or other about it and Alessa.Doctor Eggnog wrote: So anyway I agree with Kaede. Alessa's time with the Otherworld was not such a huge freaking important event that it created the Otherworld or that it continues to shape the Otherworld.
Either way, at the very least her powers and suffering were responsible for what it is today. Either way, she's still an important factor in the otherworld as we know it. Her years of suffering combined with the God and her own powers surely would have had some kind of effect on the otherworld, even if it's just a nasty stain that won't go away (as opposed to its creation). In fact, we see examples of such stains in SH2. During the twin PH fight the Virun VII crest is on the floor of the room. It's not something that we know is associated with James (unless he saw it somewhere during his last visit to SH, but I don't recall anything that could prove/disprove that).