Why does fishing and gathering materials have to be blocked from trading while tagged? I fish with my main while afk so now i cant do that. A whole feature useless also wanted to tag my shai to gather and how will i sell the saps  or beetles? How badly can someone exploit trading? Pretty sure its a really bad way to make a money even if u could use tagging to trade.

Put the trade items in storage, and take them out with a non-tagged character?

Yep to both.  Trade transport without risk is what they are trying to avoid - ?  There's things they could do to keep that risk for tagged characters, so that trade could be allowed. Easier to just say no.  But at a minimum, they could allow trade at the nearest trade manager.

maybe post in the feedback section 

If it wasn't for the fact that you are trading the fish, I would tell you to dry them out.  Only dry fish will stack, but then you can no longer trade them.  When I am fish mongering, I set a character over night in the swamp just north of Glish. Then when I get up sell to the Shai in Glish and play the trade game there as well.  But I haven't been focused on increasing any of my trade skills yet.

Have fun!

Because if you get killed while carrying trade items, you will lose some of them, including fish or the gatherable trade items.

Originally, tagging existed without the gear copy function, so they wanted to avoid giving players a way to safely transport trade items across the map.

Of course, since you can now transport trade items via wagon and trading is not profitable compared to other activities, I think it would be a good idea to just remove that restriction.

It would be better to simply completely prevent connection on a character if its tagged alt has a trade item in its inventory or its mount's inventory. 

I personally hate this.  I do imperial cooking on my main, as well as crates from time to time.  So I can't use the tag function of the game, since I grind with him too.  Why not make it so you cannot tag your other character while you are carrying any trade item instead of outright banning it.  It makes no damn sense to me, never has.

It would be easy to exploit tho, just head over to character selection, switch to your tag... Even if the game wont allow you, just restart it and pick your tag.

The game also doesn't allow you to tag in desert/ocean but you can already circumvent that by either going to character selection, or switching to an alt and then back to your tag.