Whether or not to use Auto target is a much debated topic here
With claims like increased range and spot on accuracy for fast weapons one can see how one who uses AT can be condemned by the community.
However there may the certain circumstances in which it is OK to use it.
These include but are not limited to:
High Ping
Being generally outclassed in terms of gear (4star gear against lvl10 5star)
Not using trinkets of any kind
New to LD
Sucks at LD
The last possible reason is because you have absolutely no UVs. But this somewhat depends on your armor and how it stacks up to competition (I.E. BKC and Shadowsun slicker would not fit this though armor without massive damage/asi/ctr bonuses would)
If you use AT and none of these apply to you I dub thee Prick
But AT is part of the game!
You have absolutely right to use it with a good connection, asis vh and an overpowered stuff :D