I think that the first thing that we all need to understand is that, above all, Rilisoft is a business. A business exists to make a profit. In the mobile application market, the easiest, most efficient and most profitable way to obtain money is through microtransactions for exclusive content, so it should not come to us as any surprise that Rilisoft has implemented 'overpowered' weaponry obtainable only through gems.
Number two, we must realize that Pixel Gun 3D is a very large app in comparison to other mobile apps, with lots of development behind it. It takes teams of people and lots of time and resources to create the necessary maps, weapons, skins etc., code the game's hundreds of attributes/entities/actions and set up and maintain servers that can handle the traffic. Not to mention that, since it is VERY computationally expensive for a portable device like a phone or tablet to process and render 3D surroundings in real time, Rilisoft has probably worked hundreds of man-hours to optimize game code for dynamic and fluid gameplay. There is no way that any reasonable person(s) will invest so much and expect nothing in return.
Number three, we have to consider that the folks back at Rilisoft are working quite hard to maintain an active and receptive role with its player community. They can be rather repetitive sometimes, like when they host the same kinds of contests over and over on the Facebook page, but trust me, keeping a player base busy is not easy, even when it's a full-time job. They've held competitions for new guns, new accessories, cape skins and body skins, and usually listen to player feedback when it comes to new updates. Heck, they even have an account on this forum! When you take the introduction of microtransactions out of the equation, Rilisoft actually does listen to what others have to say, and acknowledges that the opinions of its players are important. That is, after all, part of making money in a business - customer satisfaction.
Which brings us back to the introduction of gem-exclusive weaponry and accessories. Do they upset the game balance a little? Yes, but there is always a trade-off between customer satisfaction and profitability when it comes to adding microtransactions. I think that, rather than constantly put previous versions of the game on a pedestal, we should try to improve the game with feedback that offers solutions other than simply the removal of content. Yes, some mechanics are outright inane and should be removed, but I would say that almost none of the problems that Pixel Gun has at the moment are unfixable after some tweaks to the way some things work.