After all, it's nothing but a gain in functionality. Nothing is lost. If you don't want TouchBar functionality, you can turn on the function keys in System Preferences.
Here's an example of lost functionality, based on my experience, which I will replace "me" with a proverbial "you":
You have 1000 jewelry photos shot on a white background to retouch, and you have to make the background pure white while preserving the natural shadows that were shot. You select a photo in Adobe Bridge and open it in Photoshop. You press the f2 key to perform a keyboard shortcut that automates a handful of steps that prep the image for editing, then you do a manual selection of the product, and then press f3 to perform another series automated tasks that make the background white, adjusts the shadows properly, and organizes all of the layers so you can do final tweaks and color editing. When you finish that, you press the f4 key which saves the file and brings you back to adobe bridge so you can select the next image to open and repeat the process.
With normal tactile f keys, you can do all of those tasks without taking your eye off the screen and you don't have to move your hand at all from a resting position where your left thumb is on the command key. Each image can take 3 to 8 minutes to finish as a professional who has a lot of experience doing these kinds of things.
With a Touch Bar, every time you need to press one of those f keys, you not only have to take your eye off the screen, but you have to lift your hand and move it to the Touch Bar. With a regular keyboard, you can rest your fingers on the f-keys and be ready to press it in a millisecond. However, the Touch Bar treats you resting your finger on a key as a keypress, so you cannot rest your hand on it in anticipation for a key press. You have to physically lift your hand off the keyboard, make sure you're tapping the right button, and then lift your hand and rest it back on the keyboard.
All in all, with the forced moving of eyes and lifting of hands, you add around 5-7 seconds for each image you edit, and after editing 1000 images, you have added around 100 minutes to your workflow which not only takes away time, but also lowers your wage since you typically get a flat rate for the batch of images.
I wish they would give the option for a non-touchbar MBP, but to do so would spell its demise as much as a simple decision to remove the TB.