I don't understand half of what you're talking about.
First of all, you choose 7 Talents throughout the game, and 1 Race, which comes with 2 fixed Racial Talents. The Racial Talents do not count for or against the 7 Talents you have a choice to pick.
Mnemonic is a good one, but it's not always a priority. It's something which for many Archtypes, can wait until the more playstyle-changing Talents are chosen. Arguably it's not necessary at all. That will depend on a lot of things we can't know with only Act 1 available.
and if you didn't customize your talent at the beginning it becomes 3
Wait, now you're including the one at character creation again? You're not making any sense. How can you not pick a Talent in character creation? And why wouldn't you pick one? There are enough decent ones so that there should be something.
Of the 7 Talent points which you can spend, you get to pick SEVEN (7) of them. That is what Talent choice MEANS. At worst, you are arguing that we only get to pick six with Mnemonic being the 7th.
The game does need a lot more good Talents so that there can be a large variety of builds. Right now there are indeed not enough good Talents to produce a viable diversity by level 28. People will converge on the good ones. That is something Larian seriously needs to work on fixing.
Because if you put 1 point in Huntsman, then you can have First Aid, if you put 1 point in Aeothurge, you can have Teleport, if you put 1 point in Polymorph, then you can get invisibility.... etc worth more than some lousy bonus from stacking point into the same skill tree......
It's not about having all the skills of all different skills tree, it's about choosing the best skill of each tree's and have them ready ...have your character flexible. This is what's the obvious.
OR, you could, you know, ROLEPLAY in this ROLEPLAYING GAME, and build your characters to be good in a specific area instead of making them all generic min-max stat muchkins. Just a thought.
