Agreed, but it's not just a motivation problem. Deletionists get an upper-hand over inclusionists when the article is deleted because the history is not available, and you have to start all over. You can't just revert to a previous state of the article (that may not have been far from a state where it had enough references and content to avoid being questioned for notability).

Here's a particularly interesting self-referencing article that was deleted and previously discussed on HN:

http://news.ycombinator.com/item?id=518508 And here's the deleted page--with no options to look through the history and see what it used to look like: http://en.wikipedia.org/wiki/Wikiid

If you could continue to help edit an article that was made invisible for most users, articles would have a lot more time to prove their notability.

One interesting question is whether Wikipedia is legally even allowed to hide the history of deleted articles. It's not even available in the database dumps, which wouldn't be a realistic format for the vast majority of users anyways:

http://meta.wikimedia.org/wiki/Data_dumps#What.27s_not_avail...

Content is licensed under GFDL or CC-SA so you'd think they are required to make it available somewhere.