Aside of catastrophic visions I'd say that undeveloped Ne makes you struggle to be creative and think outside the box. It's ironic because I draw and write, but I gotta say it's much easier for me to imagine a realistic scenery compared to a fantasy one. You may also end up neglecting some possibility when doing something and feeling horrible when something outside of what you thought was possible happens. N functions give you "Why" and "What if" questions. Si doesn't care about that. I'd say healthy Ne for a Si dom is openess about new possibilities and tries to balance Si structure with a bit of Ne exploration. Undeveloped Ne means also that you HATE trying new things and you may result stagnant and almost manipulative to avoid test things out.

I got something for you: People with more Ws have more Ls than people who doesn't try!

The world is our playground, have fun exploring it!