Voilà l'élément de réponse le plus pertinent pour l'attaque puissante - 5 au toucher et +10 dommages :
The people who like the Great Weapon Fighting feat are counting on having advantage all the time to offset the penalties. To be fair, it's not that hard to get advantage in 5e, using the Shove (Prone) action, help action or the optional flanking rules, it's pretty easy to get advantage without expending any exhaustable resources. However, a lot of the time advantage does come at the cost of an action for either the player or one his party members. Advantage won't completely negate the hit penalty (unless you have exactly a 75% chance to hit without GWF), but as long as your target number is between a 7 and a 15 it's giving you at least a +4 or better to hit.
In BG3 there is backstab, which gives you a bonus to hit and doesn't count as advantage so you can get both advantage and backstab to offset the -5 penalty. That makes it a more attractive ability in this game than PnP.
So, without advantage, when is using GWF better than not using GWF? It depends on how much extra damage were getting from ability modifiers, weapon enhancements etc. We can calculate our average damage per attack as the product of the chance of hitting the target and the average damage per hit. Let's assume a character with a greatsword, +4 damage modifier (say a 16 strength and +1 weapon or 18 strength) and a bonus to hit of +6 (4+proficiency modifier). Without GWF, our average damage per hit from 2d6+4 is 11; with GWF our average damage is 10 points higher (21). That leaves us with the following inequality to solve: (x-0.25)*21>=x*11. The solution to that is x>=0.525. For the Fighter in our example, if our target has an AC of 16 or lower he should use GWF if the AC is 17 or higher he shouldn't use GWF, although if the target has an AC of 26 or higher he should activate it again.
A bit of a messy calculation, but it does show that the +10 to damage isn't always worth the -5 to hit. Generally speaking, if your chance to hit increases without increasing your damage, GWF gets better and as your average damage per hit increases GWF gets worse. For a character like a Paladin who has smites and damage enhancement spells, it's probably not an ability he's going to want to activate a lot.