Why was The Gremlins project abandoned?

Here is Kimball's take on it, from an interview with Richard Shale: "Walt never could decide in his mind what a gremlin should look like. It was as simple as that. Is it a little brownie? Is it... of course, a gremlin today would be easy to design in our open-ended imaginative way of going about things, but in those days, with everything so confined to a certain technique and Disney style, it was impossible. I think Walt got frustrated and gave it up."

... and T. Hee's version, from an interview with Richard Hubler: "This was prior to 1946, during the war. I was ready to go home and started walking out towards the parking lot. Walt was behind me and caught up with me and said, “Where are you going?” I said, “I’m going home.” He said, “I’ve got to go out here to see some RAF flyers out in Bel Air, talk about the Gremlins. You want to go along?” I said, “Yeah, sounds good, but I’d better call my wife and tell her I’ll be late.” He said, “Okay.” So I called my wife and said, “I’m going out with Walt to Bel Air and will probably eat out there somewhere so don’t wait dinner for me.” She said, “What time will you be home?” and I said, “I don’t know.” So, on the way down he talked all about this gremlin film, about these little guys that came out on the wings, saving the RAF flyers and everything. We got down to this kind of a deep canyon and a big old house and it was colder and foggier than hell down there. The windows were open in every room, with windows from ceiling to floor, the doors were open. The RAF men were all in their uniforms and the British women were in there with their low cut, sleeveless gowns and Walt and I had our overcoats on. We hesitated about taking them off because it was so God damned cold in there but they had fireplaces going in every room. Finally we took them off and they served us drinks and these were the typical RAF flyers - like the Terry Thomas guys - with the big moustaches, the whole thing, you know. They were talking in that very, very British, clipped way - very difficult to understand and the women were even more British. Both of us being Midwesterners I think that that kind of grated on our ears, but most of the evening, before we had dinner, most of the RAF flyers were in the den and they were telling off-color stories and Walt was laughing at them because they were funny. But he wasn’t there for that, he was there to talk about the gremlins for the film. Every time he’d bring it up, why they’d get off on some other tactic about their experiences. So we had dinner and I could see that Walt wasn’t too happy because he couldn’t get the conversation back to the gremlins. We left late, pretty close to midnight, and we got in the car and he was silent and I said something about, “You know what you could do with those gremlins...” He said, “I’m not going to do the film.” I said, “You’re not?” And that was the end of it."

Both interviews are schedulded to be released in Walt's People - Volume 5.