I might of been stupid on suggesting that villagers must be best for economy, but I actually agree with the fact that farming comes with knowledge and with great choice of spawners for your start because if most expensive spawners were best for economy then they would be an easy choice for everyone and easy choices make players rich quickly.
In my opinion things must come with great choices, knowledge on what to buy. Cheap spawners are great for starters and would be great even after you have over a billion island value because of selling effort and that in my opinion is pain.
In my opinion really expensive spawners can come in late times after you have perfect earning with cheap spawners to buy a lot of expensive ones later.
There is a problem with cheap spawners overtime, the more you get them, the more you will have to keep selling their loot and that's what limits your farming time with cheap spawners, if you have tons of them then you will just give up selling their loot because they overfill quick and their loot will take a long time to sell, at this time villagers and Pigman can be used as a main resource for economy but they come in late time, after your earning with cheap spawners is like 50m a day.
My suggestions on removing a system where you need xp to merge spawners because that will ruin your start.
If most expensive spawners were best for economy, it would be unfair because a lot of players will get spawner keys and will boost their farming.