I can understand the need to make money; free to play is not free to create, nor is it free to host, maintain, update, etc. I get that. However, I've been watching the price tag get higher and higher.
Others have already listed the problems with the game's current course. I've been watching the trends and all I can say about it is what I've been seeing are the same issues that have killed other games:
1) High quit rate/lots of alts - More and more players are leaving the game. Alts, which are against the rules, are rampant. I think there are more alts than active players. Plarium's enforcement is so bad that players openly boast that their castles are defended by out of league alt accts.
2) Alt abuse - Related to point 1, there are a ton of alts, which by itself may not be a bad thing, but those alts are getting used/abused for unfair advantage. Often they are used as troop mills for tournament points or to defend main's castle with out of league troops (unfair advantage in challenges since out of league troops garner no points).
3) Rewards for $ disproportionate vs playing the game - Pay to win/pay for advantage is a viable model. It may not always be fair, but if the balance is done right, it doesn't kill the game and can still provide fun for all, no matter how much you spend. Making it so that if one spends enough $, playing the game isn't even necessary is dangerous. That makes the top spenders get bored if all they have to do is log in, reap rewards, then go do something else and it marginalizes lesser spenders...as others have already pointed out.
4) Troop Production too slow - Yes, I know Plarium makes a ton of $ selling troops. The problem is that it takes way too long to recover from big losses. It makes many players very risk averse since it costs way too much to buy back or even revive troops and it also drives players from the game.
5) Poor support - There are lots of bugs in the game. Vanishing troops, paid items that don't work like they should, boosts that are consumed without actually doing anything, killer lag, etc. Submit a ticket and you'll get a response, often either promising to look into it or claiming devs already know about it. They may ask for proof, such as battle reports. After you jump through all the hoops, submit all the proof they ask for, you sit back and wait for comp for whatever was lost. The comp never materializes. The troops/resources/sapphires/items are never replaced. They just collect the data and ignore you. This is not a good way to treat customers, especially in a game that relies on optional spending for profit. Since I have no faith in Plarium to make good, I spend very little real money on the game. Why should I pay for overpriced digital "property" that can be stolen at any moment without recourse and which has no warranty should it fail to function as intended?