You don't waste travel time to your frames. You're imagining a style of play that is far different than what it actually is in reality.
Grid Frames allow me to multi-task and effectively perform two tasks at once. There is no delay in my performing of one action versus my performance of another, as you have described.
You're burning straw men. "Losing precious awareness" ... Wat? I'm not looking at my frames when I'm using them for a macro. I don't need to look at a part of the screen to click it. Maybe that's where the problem is - you don't think that's possible? You can play against me in arena anytime you'd like, and see if my playstyle is inferior to any other healer in this bracket. I played meta arenas since they were released. I even used keybind targeting in arenas - in fact, I did that back in Merciless and Brutal, even getting Gladiator in Brutal.
I swapped over once I saw the benefit of not having to change targets to heal. You're not giving away the targets of your healing, you free up space on your keyboard for other keybinds, and you certainly do not lose awareness of the match.
I also strongly advise against mirroring your style off of a handful of streamers. The style I adapted was originally used by Revolutiox's Resto Shaman healer in 3's. Last I checked he was 3100 in Cataclysm, making him the rank 1 team in NA during the first 3 months of the season. I met him in WotLK, where he was still a title glad. I can't say for sure what his rating was at that time.
One way to get some of the benefits of grid healing without using an addon would be to keybind @target modifiers for each of your spells. But that is kind of absurd to have to re-arrange the entirety of your bars for that purpose when there is an addon that does the exact same thing for you.
This thread is borderline derailing - so let's get back on focus. If you have questions about the way I heal, you're more than welcome to ask me about it. I've gotten more than a fair share of criticisms for it over the years. Which is fairly amusing, because generally the critics were people just on the cusp of becoming glads, who were angry because someone who played better than themselves was using something they had been ingrained to naturally shy away from.
The Mouse and the Keyboard are both tools for good play. It's borderline ignorance to believe that there are no ways more efficient than the setup you are currently using.