Yes, max energy drop-off is intentional, but (a) you cannot get into a situation where you can't use your augs, and (b) it's actually far more forgiving in Mankind Divided than it was in Human Revolution.
(A) Because the max energy bar never drops below the "reserve" portion (the thicker first ~1/4 of the bar), that portion will always recharge. Also, no augmentation requires more than the reserve portion to function. So you will always be able to use your augs, but you may have to wait a while to do so. (There are augs which significantly reduce the wait time.)
(B) Human Revolution was far worse. When you used certain augs (such as takedown or Typhoon), it removed one cell of energy completely with no chance to auto-recharge it. In Mankind Divided, most augs behave more like the smart vision system: using the aug does not immediately shift the max energy to the left by the full cost of the aug. Instead the max bar lags a little (or a lot) to the right of the energy meter, and as long as you don't use another aug right away, you will get most of the energy back. But if you do use another aug (or continue to use the same one), the max energy will start to fall rather quickly.
Moreover, biocells are much more plentiful (and take up far less space in your inventory) in MD than in HR. I spent most of HR with only the reserve energy cell charged, only charging the rest of them when I knew I would need to do multiple takedowns in a row if I wanted to keep my stealth bonus. In MD I feel like there's almost no penalty for recharging my energy; even if I somehow run out of biocells, I can make more!
And the reasoning is to prevent people from spending the entire game with Smart Vision, Titan Armor, and Invisibility turned on, taking down enemies left and right with no challenge whatsoever. For people who want no challenge, there's the easy mode. (And the normal mode too. :)
P.S. By the way, the guide pages and the descriptions in the Sarif Series 8 Energy Converter tree explain (i.e. contain technobabble as to) why you lose max energy and why the energy recharge takes time, in case you're looking for an in-universe answer.