The Pro
There is really only one aspect as to why bots bring some benefit to the game and it's actually a pretty important one: Queue Time
To me that is a cop out. Splinterlands can easily enter as many of their own non-profit bots as they wanted. This would cut back on wait times and keep rewards to those who actually play the game instead of giving rewards to those who game the system.
This is no different than delegating your account to let someone else play. People will only use the services they like. So if a bot does a good job when you delegate your account to it, it's developer should get a fair share of the earnings.
I disagree with the above statement. Allowing someone to use your extra cards can and will introduce new playes to the game. Usually someone who bots isn't a new player but an existing player trying to maximize rewards.
The Bot vs. No Bot debate has been going on a long time. There once was a very large group in the no bot section of this debate but some took the stance of, "if you can't beat them, join them". Personally I haven't and don't plan on using any bots.