Mega evolutions were a terrible idea.

I seem to be a minority on this, but I consider Mega forms of Pokémon to be a terrible idea. For those of us who don't know; in the 6th generation of the Pokémon games some Pokémon have gained the ability to transform into more powerful forms during battle if they're holding a certain item. The Pokémon changes back into its normal form after the battle. There are plenty of sites where you can read all about this process commonly referred to as 'Mega evolution', so I'll pass over it here to get to the meat of my objections to this system.

Mega Blaziken

One of the main tenets of the Pokémon games is that player should be able to play with the Pokémon they enjoy; cemented by the insistence of the games that Pokémon are partners rather than tools to be used at will. This idea has been very flawed from the start seeing as it is extremely clear that some Pokémon are objectively 'better' than others at doing the main thing you can do with them in these games: battle other Pokémon. But this imbalance remained more-or-less manageable, even if it helped motivate an entire subset of players to set up a custom ruleset to match Pokémon with their equals in power via the Smogon system. With Mega forms being introduced this precarious balance is completely upended.

Not áll Pokémon evolutionary lines have receive Mega forms, in fact only a few have gotten them. This means that the games' designers have played favorites picking and choosing certain Pokémon over others deciding which ones would become exalted. Mega forms have been made into such powerhouses that they are very widely used, meaning that players are heavily encouraged to include one of these few Pokémon in their teams in order to retain that competitive edge. This means that players are encouraged to pick certain Pokémon over others based on a utilitarian power level, leaving their favorites by the wayside.

The psychological impact of Mega forms has been to make certain evolutionary lines more special and important than others: 'chosen' by the game developers as it were to be figureheads of the games, informing players that their beloveds are just ordinary. There's a reason why there has been so much clamoring for other Pokémon to get the Mega treatment: many people want to see their favorites become Mega too. 

These are fan concept art

From a pure gameplay standpoint I have no problems with the Mega forms per sé; I think they fit poorly in the established Pokémon setting but I can overlook that. They provide interesting dynamics in combat, they're not so overpowered as to upset the entirety of game play and from a pure marketing standpoint the move has turned out to be pure genius on the developer's part. From the perspective of merging gameplay and themes however Mega forms don't work and I think they should be removed from the games' canon entirely or every evolutionary family should get a Mega form. 

Shouldn't players feel good about whichever Pokémon they like rather than what the game developers think they should?