I've been doing a lot of fishing lately...and I'm failing to see the point in bait. I did all my testing on tuna shoals, but by memory, the same applies to lesser fishing nodes. Tuna nodes all give between 8 and 12 tuna. The average I get per cast is 2-3, but closer to 2. Using bait, not much changes. Using level 1 maggots, they give a 20% yield increase. If you take 20% of 2...you're only getting a 0.4 increase. I would guess the system rounds down, so on average, you're not gaining anything at all. Even if it rounds up, you're going from 2 to 3 fish per cast on average. Still, you're only getting between 8 and 12 fish per shoal, so at MOST you're saving 8 seconds of casting time, but subtracting the time to "use" bait, you're almost breaking even (maybe saving a few seconds).
Now using the level 8 bait, you gain 35% yield. So on average you're gaining 3 fish (2*0.35+2=3{rounded}). But still your yield is only 8 to 12 fish per shoal. So here, you may be gaining at most 10 seconds per node. At level 15 fishing, on tuna, it would take between 20-25 minutes to level to 16. Using bait, I might save about 3 to 4 minutes, if that...BUT I will be losing experience from less casts, so it would take me more casts to level up...negating the time saved. I may end up with more fish in the same time, but less experience.
So, let's look at the next 2 levels of bait. At 16 you get bait that increases 50% yield, and at 24 you get a 75% increase. Again though, you're not increasing the yield per node, just the increase per cast. But if you're still only getting on average 75% of a 2 fish per cast, you may cut each node down to 3 casts instead of 5...still only saving 10 seconds on average per node. And at 16 silver per stack of 10 bait, where's the gain?
Long post, but on the mechanics of fishing and bait at this time, is there any reason to use it? I searched for other posts like this, but found none. That's why I made it this lengthy.