The widespread acceptance of trochus is a result of players having easier access to it back when trade tables were first established to reduce scamming via the old drop trade norm. Like Trix said, this is due to the high drop rate of trochus versus other sellables and the fact that you only have to do one thing to get some capital in order to be involved in the trading business - dig. Trashes and mushrooms take too much space in the table and gets kind of messy, same goes for other sellables. Moreover, this is the result of a player-run market that took into account all the players' preferences and eventually gave rise to trochus as the trading currency in the game. In other words, trochus is accepted because it's what the players have favored throughout the years.

If an intervention would have been done to make our belittled aerolatas forcefully accepted in trade, eventually trade prices will go up in the long run, making things harder instead of solving the "work 2x harder" issue you mentioned. Think of it this way, because aerolatas can now be used in trade, then yes players can earn shells (trochus and aerolatas, specifically) faster. But this also grants more players the purchasing power to get rares and even ultras. With this increase in demand, the owners of the items can price and sell their items higher because more people will want the same item, therefore inflating trade prices which eventually brings us back to the same level of difficulty (or even more!) of earning for an item when trochus was the only shell accepted because prices are now higher. Additionally, this create an uncertainty in the future that may cause declines in trade due to the fear of selling your supers for aeros, which was not usually done before. It will take time for players to adapt and still, there's the fear and uncertainty.

You cannot simply reason out the loss of gralats when exchanging aeros for tros to force the former in the trading world. If we're merely talking about trade in their gralat values, then shouldn't supers be sold according to their auction value? Why are we buying stun guns for around 2K trochus, is there some sort of EC-to-shell ratio? These are some of the things that have been addressed by a long process of negotiation and trading, and are still changing.

Forcing aerolatas in the trading economy of the game is like forcing the local grocery store in the Philippines to accept your US$ - they would never. You have to freaking exchange it, right? According to the forex rate? Thus, you have your sellable exchanging system.