All i see with these wishes for additional features like waterproofing and wireless charging is increased cost which the entire market of users would have to bear in order for the segment that wants it to have it. All well and good, provided the segment is the majority of the market. I don't necessarily need waterproofing on my iPad but i would appreciate the peace of mind. I'd rather not spend a significant amount more for it though, after all the Pro line has only increased in cost over the past few years with no appreciable gain in software capabilities. Hopefully things improve there too in the future . . but i digress . .
Apple's bean counters would look at the development cost - engineering & tooling - and what price increase would be required to cover those and additional material and manufacturing costs and weigh that against sales impact. I don't think most buyers would be interested in paying much for it for an iPad (unlike a phone which is more likely to see use in wet conditions). You have to wonder where the knee in the curve is for iPad prices.