Not really productive to compare EAW technically to BoX. At the time EAW was on the market there was really no competition to it regarding immersion and all other things. Sure the graphics were dated compared to Jane´s WW2 Fighters, but for it´s time EAW was very good. Oleg´s L-2 raised the bar again, especially in numbers of players playing it and other things. It had a thriving comunity and still has a great deal of players. And there is no wonder why: content and ability to create something big without performance dropping to a crawl because AI and objects eat up all the power. BoX anyone?
BoX is graphically very nice. One can debate if DCS or BoX looks better inside planes, but models are very much equally well done. System modelling in DCS beats BoX hands down. No artificial timers after your engine blows etc. And with more planes coming to DCS WW2 module one can easily compare them to same planes in BoX and see if there is a difference to the way or another. I personally think a mix of DCS and BoX would make the best sim there is. But again both have their merits and that is why they are on my hard drive.
What has declined the community IMHO is that the average age of "pilots" has gone up. With age comes family, work and other RL responsibilities and activities. Just simply lack the time to play as much as before. Same happened to me, time is scarse now. And getting younger generation interested in a genre that has a relatively steep learning curve added with somewhat hefty hardware requirements can be a deterrent. Most games require only a mouse and keyboard. No need for throttles, sticks, pedals, tracking devices, VR etc. Money can be an issue like the learning curve. Another thing is the lack of instant gratification in flight sims. You do not get to be a virtual ace from the start. Frustration levels will go thru the roof before you get the hang of it. Turns away people with less patience.
And not to forget the community around flight sims. One of the hardest to please and very demanding + vocal. Personalities ranging from friendly to elitist pricks. Not as toxic as FPS games or DOTA communities, but a fair share of less than friendly attitudes at times. Another turnoff for many. Flight sim community should pull the rope in same direction, not apart. Every sim there is has a player base supporting a genre that is very small these days. All of them serve as a platform for varying needs each player has, which is a good thing. If there would be less snide remarks how sim X is better than Y and Z is total poop then things could improve. But no, there are always some individuals who have a holy mission to put "their" sim on a pedestal and worship devs to a fanatical level..and everything else made is bad. Way to go, another turnoff for a potent flight sim pilot..
TL;DR We need a more approachable community to get younger generation into flight sims, in any of them.