Even if it did have the least amount of maps (does that include the groundwar and gunfight maps?) the game itself has a full campaign, special ops, many different game modes, completely customizable weapons, etc. etc. it's not like this was an 'incomplete' game when released. That they are continuing to add content for free and people are complaining about it just points to how entitled gamers have become.
They provide entertainment but it's also a business. We are not entitled to anything. They could make a steaming pile of crap and if people continue to buy and play it they will continue to do it; especially when most of the complaints are absolutely frivolous/whiny and, as mentioned, entitled. If it was a badly designed game people would stop playing it, stop buying it, and that's how you get companies to react. However, also as mentioned, this game has a very healthy playerbase and a large group of that is very happy with how this game is going.
I agree. But, people are also entitled to their opinion.
My opinion is that this was an incomplete game when released - something I don't recall having ever said about a COD before. Most people don't play for the campaign or spec ops so those being added back in is really inconsequential. Additionally, the "many different game modes" you reference have been in every single Call of Duty. It isn't like they added anything new. I think it is actually easier to make the argument they took a giant step back based on how the lobbies run since you aren't ever in a lobby with people for more than one game. That is how I have met a bunch of the people I currently play with and to me that is a giant downfall of SBMM. I loved getting in a good lobby, clan vs. clan or even two groups of randoms that stuck together for a while and spending 5-6 games going back and forth. SBMM is a solution in search of a problem. Most people who were actually good/competitive would play OBJ game modes. That is where you would find the most competitive players.
Additionally, I think the issue with the maps goes way beyond your current understanding of it. When the game came out, you had 6 regular sized maps for TDM (the most popular game mode). There were 2-3 separate maps each for ground war and gunfight. So while you may have 12 maps total, for most people there are only 6 maps in the pool. If the game was released with 8-10 maps for 6v6 play, I don't think as many people would be complaining. It just feels like a lot of the changes were made for the sake of change and not well thought out changes that overall were a net positive on game play.
I don't think the issues with MW have to do with gamer entitlement. The reason people are especially vocal this year is because they gave us a lot of things that few to no people asked for, took away a few of the consistent things that worked in COD (such as sticking with lobbies, being able to vote on maps, etc), removal of dead silence, a ridiculous multiplier to head shots and so on. It isn't just fans, you have had a lot of COD pro's being very vocal about the changes to this game. Additionally, I think the larger issue is the constant yo-yo each year with the franchise. You go from having jet packs, wall running and super fast game play one year to having super slow, boots on the ground game play the next. You never know quite how far they are going to take it each year. I didn't expect to like Ghosts or Black Ops 3 based on everything I read but I really ended up enjoying both. I expected to love MW and frankly, absolutely hate it.