stupid idea.. thats why its hard to get a legend hero... because its op
Firstly, as has already been mentioned, there needs to be motivation to have Legend's to support the games fundamental business structure. No paying = No game.
I do see what you are trying to do but they are intended to be a tier above lower ranking Hero's. If you're asking for a balance between Legend and non-Legend Hero's you're effectively asking for the tier to be dismissed as a whole. If there wasn't enough of an advantage to having them then what's the point, right?
There are also the following issues:
- The might of 7 Hero's, say 5 Ordinary and 2 Elites, would give them a huge advantage over others using Legends. You'd more than likely be matched against someone far further along in the game if you were to use Legends. In essence you would benefit from avoiding to use Legends.
- Numbers can be a game changing mechanic. Single target skills, such as Ninja for example, now become less effective while something that can hit multiple targets will be even stronger. 7 skills charging at the same time also means more skills going off, unless skills of all other tiers were changed this would mean that again Legends would be at a disadvantage.
- As currently in raiding your Hero's will also attack buildings and walls having 7 Hero's to catch you out is far worse than only having 5. In addition to this they have a larger range of attack with 7 Hero bases instead of 5.
In a free game with in app purchases you'll always see this kind of system. If you don't want to pay you'll have to spend weeks or months to get to the same stage for free but they have implemented a way to obtain everything for 100% free.
I would argue that Pay2Win is bad, but since gems are fairly easy to get without paying one could argue that a person could get a bunch of legendaries without paying anything if they're lucky. The fact that you can get gems for free means that everybody has the chance to get legendaries, its just a matter of whether or not you want to pay real money to get them faster.