OK, here's a basic proposal that might alleviate the Gold use issue and potentially even the playing field a bit. It may need some fleshing out, any suggestions welcome:
A. Inno should make Grepolis (and possibly it's other browser-based games) subscription based and charge a flat monthly fee to players.
There would be 6 membership levels (Based on current Gold package offers):
1. Copper - free entry level membership. Players could only use gold gained through free offers and through trade.
2. Bronze - cost $9.99 USD per month - player gets 1200 gold plus what they can get through trade. Enough for advisors.
3. Silver - cost $19.99 USD per month - player gets 3000 gold plus what they can get through trade.
4. Gold - cost 49.99 USD per month - player gets 10,000 gold plus what they can get through trade.
5. Platinum - cost 79.99 per month - player gets 20,000 gold plus what they can get through trade.
6. Platinum Plus - cost 79.99 per month - player gets 20,000 gold + trade, but can purchase additional packages once that runs out
B. New world releases would not only have their usual settings but would be restricted to certain membership levels.
1. Mortal Worlds - restricted to only Copper and Bronze level memberships
2. Titan Worlds - restricted to Silver and Gold level memberships
3. Olympus Worlds - for Platinum and Platinum Plus level memberships
Mortal worlds would include all currently available features. To add a little incentive perhaps Inno can add some extra features such as additional heroes, spells, Gods, troop types or myth units to Titan and Olympus worlds. (These names are also just examples)
This way you would have non-gold users facing light gold users, moderate facing medium, and heavy facing the really big spenders.
C. Players can only upgrade/downgrade within the world type they sign up for.
So a free Copper user can upgrade to Bronze, or a Bronze downgrade to Copper, as long as they are playing a Mortal level world. If a player quits they keeps the balance in their account, and can sign up for another same-level world if/when one is available. The same would also apply with Silver-Gold users and Platinum-Platinum+ users.
Players who want to move up to a different world level would need to pay for a higher membership level but would keep their existing Gold balance. Players at the higher levels who want to move down can also keep their existing balance but how much they can spend per month would be restricted to the level of the lower worlds. This would keep the playing field more level and might also have the added benefit of cutting back on the frequency of world jumpers. And I think it will still provide Inno the revenue stream they need.
Remember, these world levels are separate from world settings, so Inno might release a speed 3 Revolt No Morale Titan World that only Silver and Gold members could sign up for. Players might have to wait longer to get the not only the settings but the world level they want, again hopefully cutting down on the amount of players who jump almost every time a new world opens.
I'm sure there are some things I may have not thought of. If so I welcome your thoughts/ideas. Also, I did not bother to check if anything like this has ever been suggested, so if it has, my apologies.