I watched The Wild Bunch BD recently and also noticed that it had a lot of brown in it but I wrote that off as Peckinpah's choice. The Mexican locales and the gritty nature of the film made that make sense, to me at least. The lossy 5.1 sound, though, showed its age. As others have said, a new BD edition of the film could no doubt improve it, both visually and aurally, but doing so would require a lot of work.
HT setup: Sony 75XBR X940D UHD HDR TV; Kaleidescape Strato Movie Server 6 TB; Yamaha RX-A3060 AV receiver; Crestron Control System; Hsu VTF-3 MK3 Turbo subwoofer, 6 Hsu HB-1 Bookshelf speakers, 1 Hsu HC-1 Center speaker, 4 Focal ICW8 in-ceiling Atmos speakers; Oppo BDP-103 BD player; Mac Mini HTPC. TiVO Bolt 1TB DVR; TiVo Premiere Elite 2 TB DVR