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I think such specializations are simply boring and inflexible.
But for a proper comparison, we can recall the specializations for creatures. At the beginning of the game, most of them provide a huge bonus in the form of a strengthened starting hero army + a small stat boost to creatures of that type (which will be predominant in the army due to the composition of the starting army). Over time, this predominance disappears, but the specialization strengthens and gives more stats.
For example, Ossir, if I remember correctly, gives Elven Archers +1 to attack and defense for every 2 levels of the hero, starting from level 1. At level 15, it's +8, +8. At level 1, it's +1, +1.
So, my answer is no, even +4, 0 is probably not enough to make the specialization look relatively good.