The mechanic turns out to be extremely underwhelming, to the point it feels like a slap for an old player, because it disqualifies any nation with a top tier vehicle from receiving the bonus, even if you have multiple top tier vehicles in other nations. It’s supposed to stimulate researching more tech trees and branches, and it completely fails to do that for people who were already doing that. This may be an extreme case, but it’s an existing case nonetheless:
Yes, I don’t play tanks these days. But if I would like to go back and get a decent American lineup, it would be more efficient for me to NOT play the game and wait for Gaijin to add something past ADATS because it blocks the US tech tree from receiving the bonus, which I have because I have top tier Soviets too. So might as well not play it at all. I can’t sell it, I can’t do anything about it, and the most ridiculous part of that is, I got the ADATS because I was building a diverse all-purpose lineup for America back in the day. Got burnt out in the process so much I stopped playing tanks completely, but my point stands.
Sure, this is a case of an extremely neglected research. I have much better research in the top tier air. Is the reward better there, though? No. Take a look!
This is my state of top tier air. As you see, I am a half decent player with a fairly wide access to different planes. Does the bonus promote researching new aircraft for me? Not at all, because all the tech trees I am interested in already have a top tier vehicle in them! I can’t get the bonus for the Benelux tree because I already have M2K5F. I don’t have a bonus for Japan because F-16AJ is considered a top tier vehicle. However, Yak-141 isn’t, and since I don’t have Su-27SM or MiG-29SMT (these two are the only vehicles I don’t have in the tree) I do get a bonus for USSR. A .3BR difference makes or breaks the bonus, and this is extremely arbitrary! Okay, you might say, you don’t have top tier China or Israel. Well, problem is, that bonus doesn’t benefit low tiers too, so it has no effect until I go through half the tech tree.
What another extremely arbitrary thing about the bonus? Coastal fleet. I didn’t play the mode for ages, and never really had the urge. But I managed to get PR-206 back in the day, and you know what? It provides the bonus for me! I don’t know why, I don’t feel I deserve any bonus, because it never was top tier, and was merely rearranged, but for some reason it works.
TLDR, there implementation lacks consistency and fails to achieve the declared goal to the point people would do the opposite of the suggested behavior, because the mechanic disqualifies nations with a top tier vehicle in them. Please, solve this.