This specific reason has been cited many times for various parts of the UI.
Please consider this:
- 1920x1080/1200 displays are not rare anymore, if you have data against this please tell us so we can stop pretending we're the majority :3
- If you start off your designs with scalability in mind, you would have built the option at the beginning.
Looking forward, there will be a lot of UI elements that will run into your 1280x720 limitation. Especially when the player-made add-ons come into play. Please, please,
please do not limit resolution on player-made addons. Add-ons exist for customization, it is so we can each get exactly the UI we want. Any such limit on PC add-ons defeat the purpose of add-ons.
I'm very worried about the future of the UI. It seems the UI team work only to be satisfactory at the lowest level. Little room for customization is provided, and where they are provided, they're are very restrictive and cater to the lowest hardware specs. Nothing in the UI is ever made to cater to better specs.
Please put 1920x1080/1200 along side 1280x720 when you design future UI elements. You boast how you compare colors and performance on different major brands of displays, yet you never consider the usability on high resolution. It gives the impression that the work is always half-done.