Tomb Raider 4-6 Remastered happened because "it just didn't feel right" to do 4 and push the other entries aside, Aspyr says

Core Design's Tomb Raider games were (and still are) an odd bunch. After the critical success of the original trilogy, which Aspyr brought back with a strong remastered re-release last year, Tomb Raider: The Last Revelation did well enough, and then Chronicles and The Angel of Darkness crashed the IP (and the studio) until Crystal Dynamics came along. However, Aspyr says the plan always was to refresh all of them with Tomb Raider IV-VI Remastered.