I'd agree that there's no practical reason to dump Samsung over one issue (especially given how they've been responsible in how they've addressed it) - S7 and S7 Edge are both still exceptional units well worthy of consideration in the premium phone market. Can't say that I'd agree about them being the most reliable, highest quality Android phones (are you aware of any statistics reporting reliability? As to quality, if you're not referring to build quality (which would be addressed under reliability) then I presume you are referencing quality of premium materials or added feature/function, in which event there are a number of others that win or lose that battle, depending on individual user preferences.
There is a reason, but it has little to do with Touchwiz. Like Apple, it is primarily due to exceptional brand-building and marketing prowess that have allowed them to set themselves ahead of a pack of other devices/brands that are easily arguable as its peers.
To be clear, I'm not knocking Samsung in any way - the S7 Edge is on my very short list of phones I'm looking to as my next, imminent upgrade.