The deprecation of HTML widgets (not things like DIVs or SPANs) is applicable to all products supporting UXP. We’re aware of the bug w/ spectrum buttons and clicks, and that will be fixed as part of the process. We won’t restrict use of the HTML controls until the Spectrum controls have parity & have no serious usability issues like this one.
This deprecation is one of the steps required to fix a lot of other issues in the runtime, including input boxes effectively having infinite z-order, but also enablement of animation, accessibility, etc. This is a long-term process, so we’re letting you know now, and giving plenty of notice before we actively take any steps to removing the deprecated controls.