Vince - This might seem a little strange if we think of time as a linear progression. Think of his ascension like throwing a stone in a pond - the ripples went out across time and space. This was literally like creating the wheel - it had not been done yet in the other timeframes, past or future. Then after this it was an option in all the timeframes. And yes, doing this in public forever stamped the impression into the collective consciousness to have ascension as an option.
You're right - so much of the past isn't applicable today. In fact, mystics and mystery schools will usually take great care to release the past and find some techniques/words/stories that will be practically applicable in today's world. It has gotten difficult to stay on a path and feel the truth right now because people are allowing themselves to get distracted (i.e. internet, tv, entertainment, sports, etc) and they have become less discerning.
There are 33 parallel dimensions to ours. The experience I'm talking about isn't quite the same as astral projection as much as it is more of a form of parallel life expression. It would be more similar to when we sleep at night and visit our other lifetimes, which have seperate bodies and circumstances happening. Only he did all of this very consciously.
The reason for him spending so much time in those dimensions, is that this particular drama wasn't just playing out on our dimension, but on all the other dimensions as well. So he was present enough here to take care of things on our level of consciousness, but was also devoting time to all the others, as well as integrating resources, information, etc to help in each.
All roads are leading to the same thing! The funny thing is, we usually pick a spiritual path based on whatever conflicts we still have (i.e. like being active - choosing a type of yoga, enjoying being emotional - choosing a bhakti type experience).
Yes there are other options. Instead of ascension, some people have chosen a path where they become what is called a Time Lord or a Time Being. (Smacks of Dr. Who I know.
) This is where we can choose to be an immortal being for a specified period of time, then move onto a different expression. Krishna was an example of this.