Two people complaining about the same thing, probably it exists... I never play with auto tuck-in so I never got this... I'll have a try as soon as I can!
What many people do Dyego is to select "auto-tuck" but then to manually override this by pressing a designated "tuck" button on their gamepad controller when they want to "tuck".. This is the method that to my knowledge all league racers adopt (at least everyone I have spoken to who I have raced with) as you get the "best of both worlds". Auto tuck makes sure you are tucked-in as required on the straights but then by doing it this way you still have full control and versatility on corner entry, transition from braking to leaning to throttle through and past the apex and on corner exit.. you can manually "tuck" as you require.."re-tuck" and adjust as necessary. On the straights it doesn't matter with auto-tuck and you can relax & rest your hands a bit..
That's the theory I think with going "auto-tuck".. People tend to get slightly quicker lap-times that way also I think.