Well here is my take on this.
The game is designed so that the players that can spend the most time actually playing have a significant advantage. To wit: farm villages for 5 minutes instead of 8 hours. Or being online to see incoming attacks. Etc.
The game is designed so that the people who pay will have the best advantages. The more you pay, the better the advantage.
There are many games out there that have the same style. When I first came to grepolis I passed over about 20 of those games before I found this one.
In fairness to Grepo, they offer options for players to earn free gold so they can get an the premium advantages without ever shelling out any cash. While I am not a fan of gold, buying ingame bonuses, or paying your way to victory, I was impressed that this game offered non-paying customers the benefit of earning gold without paying. For that reason (and because the game looked good) I decided to give it a try and stay.
Over the course of the last year, it is my belief that Grepo has, and will continue, to swing towards the "pay your way to victory" style of game.
Now on to my thoughts on this particular feature.
I had always wondered if a gold user could simply summon the merchant to their harbor over and over for the purpose of getting an infinite amount of resources. I never tried it. Beyond the 5 premium features that are a staple to the game (admin, merchant, captain, etc) I don't use gold very often.
It is my belief that this feature, whether allowed only once per building or having multiple uses per building, is unrealistic in regards to keeping a fair play balance.
Part of being a "good player" is being active. Activity is where it's at. If you are caught offline, you have no recourse on defending yourself. Part of taking out a good player is finding their inactive times.
This feature, outside of the imbalance caused by expending gold, slaps the above notion in the face. It says
-- Don't have time to wait and can't be online - just pay gold and don't worry; we got ya covered.
-- Earthquakes an issue? No sweat... rebuild your wall without the resource requirement that other players have.
-- Want to develop your city faster than anyone else so you can conquer sooner... just pay gold and we'll let you
-- Want to do multiple things, like build up your research, troops, and city? Oh... if you pay gold we'll help you do that so you can win while other players can't.
At some point in time there needs to be a level of fairness to all players that you allow to play, without causing your company to fail due to lack of income. In my opinion, this feature crosses the line of fairness in too many ways.
I'm already frustrated because previous upgrades make it very difficult for me to play on my phone now.
I've never been a fan of gold and "buying your way to victory"
And now you want to introduce new elements to the game to continue to offset the playability of its players.
If you hadn't already reached "the beginning of the end" with your game "upgrades", it is my sincere belief this is it.
So while I won't be playing after the world I am in has concluded, perhaps there are some ideas that might, directly or indirectly, help.
Why not introduce a monthly fee for players. Pay the fee get the premium features. Don't pay the fee, and don't get the features.
If, however, you are not a subscriber, you can still get the features individually (as now) via gold.
Then every player has the option of being on the same, level, and equal playing field. Instead of the game being a money pit where features can be used to death as long as you have the money to keep spending, you would have the option to pay a monthly fee and be equal. Period.
And/or fix all the buggy glitches prior to introducing more and more upgrades into a system that continues to fail with each upgrade at a minimum.
In either case, as a company I wish you the best. The game is enjoyable, but not something I will find as a long term manner of enjoyment for too many reasons. This one just adds to that list.