That is actually a change I’ve made to my spreadsheet. Plus a tweak (nerf) to strong projectile damage to balance it out, which kinda screws with my “can two-shot chickens at 33% difficulty” reasoning for the current damage values, but if enemies will eventually get their health formulas reworked like IA mentioned under the WBP excel post, then that’s probably not a big issue. Additional firerate seems more helpful overall than one-shotting capability in this case, at least from my testing.
I wouldn’t really consider Positron “intuitive” in its current form, and we don’t really know how it’d perform if we do decide to rework it. I think Lightning would fit better into a starter weapon role, as chaining is a more reliable mechanic. Photon’s homing is a bit of a double-edged sword, so I don’t think it’d be a great choice.
I wouldn’t consider leaving Moron without overdrive as a viable option, for reasons explained above. If it stays in the game and is to fulfil the role of a starter, it has to have it, even if its in a slightly nerfed form.
At this point I think all 3 suggestions proposed here (removing it and replacing it with Hyper, making it upgradeable up to 
3, or giving the player a selection of weapons to choose from after the tutorial) are pretty good. Personally, I’m leaning more towards replacement, but any of them would do the job.