But it's convenient to eat fat because it has many benefcial properties (especially good oils like olive and **** seed)
It's convenient to eat carbs. Eaten carbs can be directly utilized by the body without impure transformation processes. Carbs are the purest form of energy. What one does with said energy of course is a more complicated issue but as I have said earlier, a sedentary person does not need much. The brain uses ~100 grams of glucose per day and the body uses some more for essential processes. Burning fat can give adequate fuel for the brain but in ketosis the brain does no use glucose as fuel. Whether this is a good or a bad thing is still a mystery to me since I can't find anything good from pubmed at this time. At the moment I would say it's irrelevant.
However I do know that getting to ketosis can be pretty harsh as the body needs time to adapt (weeks at times). The adaptation period may contain foggy brain, aggression, mood swings, headaches etc. Aka. not a very nice few weeks.
Now the body can of course survive with just fat and protein (with the required micronutrients) but for example sustained maximal power output at least according to current knowledge is impossible without large stores of glucose. The body may very well store glucose even in a state of ketosis but some needs to be ingested especially during long intense workouts or races. Many of us do not race, but it would be beneficial to almost all here to do hard sustained efforts once in a while.
In the end the possible adverse effects of a ketogenic diet are still unkown. I would not advocate it for longer durations without some pretty solid studies with human test subjects from various areas. It might be that in a 100 years the ketogenic diet is the norm and carbs are a thing of the past. Or it might be one of the mildly unhealthy fad diets. Thing is, you never know before some solid research comes out. The studies I can find are mostly of short term effects (which are encouraging) but there is a lot of BS in the mix. Also many studies are with rats. Human testing needs to be done for certainty.
Also the keto diet need to be very well tailored to reduce the possible risks (meat induced bowel cancer for example) with a good balance of foodstuffs and cooking methods (frying is worse than boiling)
So all in all, the keto diet seems to be a hassle. Carbs are extremely convenient as a pure form of energy (for many too much so it seems). And of course I can sadly never try it. I'm a type 1 diabetic you see and that kinda takes away the possibility.
And that brings me to my last point. My headaches and other problems were not due to blood sugar swings caused by carbs. I am a type 1 but I DO NOT get blood glucose swings. I am very good at this. I had perfect BG levels and still felt like dying. So it was the carb deficiency, not BG which caused the condition. Not enough fuel for the brain I would suspect (it takes time to adapt as I mentioned above). I need mah carbs brah!