Is Dazai Ruining Bungo Stray Dogs?

Dazai Osamu is a well-beloved Japanese author, as well as a widely adored character in Bungo Stray Dogs.  However, is his status actually hurting the series?  Here's a few things to consider:

His intelligence.  He has great attention to detail and can plan major events and their exact outcomes in advance.  We were also shown early on in the series that he is capable of more or less keeping up with Edogawa Ranpo's "Super Deduction."

His apparent inability to die, either by enemies or by his own hand.  This is not only stated but shown several times in the series, mostly for comedic effect.  But the end result still remains.  It's not even his ability!

That actually leaves me at my last point.  His ability.  He can cancel out any ability, seemingly without fail (as long as it is actually an ability and not something else).  In a world where people are armed with numerous dangerous powers, he can bring them back down to a normal level with just a touch.  While this may not guarantee a fight with someone who has more fighting prowess (one skill that he doesn't possess at an expert level), it sure helps in a lot of situations.  And what he lacks in raw power, he makes up in planning, so there's usually no blind spot in the first place.

How many abilities and skills can a character have before they become "too good"?  At what point does it start to diminish the excitement that can be felt in the series?