I'm boycotting 100% of devices that won't step up to the minimum standards set by the Nexus devices. The Nexus devices come out and trounce the Q2 releases on hardware and features and set a new bar... then a couple of manufacturers pretend it didn't happen so they can save on the R&D (I think that's the theory.. if we leave it the way it is, it's cheaper...) even though many of the "features" they're coming out with already exist in the included Android package they're given and they're actually devolving below minimum standards. And since they're duplicating effort, in my mind that suggests waste. Remember, they have to go out of their way to modify TouchWiz to circumvent the included code and recreate it to match their button configuration. It's free to choose not to do that.
I'm not sure you understand the situation. Are you boycotting devices that don't include all-virtual buttons? (TouchWiz has nothing to do with whether or not the phone includes a menu button: there is no circumvention of Android code.) Are you boycotting devices that include their own launcher?
Android decided that the menu key was too confusing because there was no visual indication that there were extra options available. Instead, they now suggest the action bar, which is like the menu key but takes up screen real estate, doesn't always look the same, and can show up anywhere (you can probably guess my opinion on this choice). (Interestingly, Google's own applications support the menu key when present and switch to the action bar when not.)
Since all of the application developers obviously weren't going to change overnight, Google went with virtual buttons, allowing them to add the menu key when the application hadn't been updated without sacrificing screen real estate.
Manufacturers of phones have mostly decided not to use virtual buttons. Samsung and others includes the menu key (so they support both the action bar and the menu key). HTC has chosen to remove the menu key so applications that haven't been updated shrink significantly (to make way for one virtual button).
It's tricky when you start talking about manufacturers duplicating functionality of Android. Originally, Android had very poor support for Facebook and Exchange, and each manufacturer released modified versions that worked better. Once Android support was up to par, they moved back to the stock versions. In a more recent example, Android released file sharing, Android Beam, but it didn't support WiFi Direct. Samsung released something similar not long after that fully supported Android Beam, but it also supported a WiFi Direct variant. Once Android Beam supports WiFi direct, I'm sure Samsung will downplay S Beam as much as possible or remove it altogether.
So, again, I'm not sure what you are intending. We shouldn't buy non-Nexus devices because they include extra hardware that the Nexus devices don't? Because they included additional functionality? Yes, sometimes the manufacturer variant is missing Android functionality, and that should be taken into account, but I wouldn't "boycott" a manufacturer that once did this.
Personally, I try to select devices that aren't locked down and are likely to get AOSP/CM support. After that, the most important consideration is the hardware and the currently available features.