why is halo 5 so much data?

Halo 5 is a pretty decently sized game with campaign, multiplayer, forge, and firefight. (Yes i count firefight not as multiplayer in the traditional sense and more in the way how cod zombies is a different experience while technically be multiplayer) My question is why is this game nearly 90 gbs. Other games with tons of content like witcher 3 and fallout 4 are massive games but combined together are just a couple gbs more than halo 5.It pisses me off because i had to buy a new hard drive or have to delete games i play for one game. This makes even less sense when with games like the witcher 3 having better visuals than halo 5. What is taking up all of this space. I miss the old days when 10 gb was a ton of space. The master chief collection which includes halo ce, ce anniversary, halo 2, halo 2 anniversary, halo 3, halo 4, and halo odst if you bought it comes down to a total of 80ish gbs. Why is a game which includes 5 games not including the anniversary versions, three forges, a lot of game modes, over 100 maps, 5 campaigns with redone visuals in the case of ce and 2, custom games, and a theatre mode less then halo 5 in size?