Is defense down worthless or fixed? And should Dathcha leader be buffed

My team once I get engineer and Magnaguard up will be
Dathcha (L)
Poggle
Magnaguard
Jawa
Jawa engineer

I have ig88 7* but his squish is too much

So with that leader ability it is 80% chance to cause defense down on droids,
Is defense down a good debuff? Does it help?

And secondly, do you think this leader ability should affect non-droids? Maybe give it a 30% chance rather Than 80% for non-droids