Another major change in the tv adaptation of Good Omens was changing the balance of the plot threads to focus much more on Aziraphale and Crowley's.
Adding the specific flashbacks, and all the changes in the emotional plot in their relationship to each other, essentially created a whole other plot thread too - not one that I'd call a B- or C-plot, because it happens at the same time as the other plot in their scenes, but it creates more tension and more... scaffolding, you could say, for their relationship, which was mostly only visible along the edges of what was happening in the book and in passing as it related to the specific plots relating to the End Times. (That makes it almost sound like it wasn't a love story before! But it was, it's just that it was more about them being drawn together more and coming to a deeper appreciation of one another through the events of the apocalypse, without showing any of the developments in the establishment of their relationship, which already seems to be trundling along in perfect harmony. The series has added in all these points along their personal history that turn it into another kind of love story altogether: a classic romance plot, even if you choose to interpret the love in question as entirely platonic.) Anyway, all of that added material probably made it take a bit more runtime and significance, and Sheen and Tennant are, as everyone has already said including me and them, basically magic together, so I can well imagine them getting more screentime after everyone saw them starting to work together.
Also there's a noticeably reduced presence of the story of Adam's life and the Them. Part of this is probably because so much of the necessary information there is contained in the omniscient narration in a way that is difficult to adapt to the screen without voiceover, which Neil already made liberal use of throughout the whole show. And part of it may well have to do with how expensive and difficult it can be to work with child actors. But regardless, while I think it does still feel a little unbalanced, the gist mostly comes across (the Them-horsemen matchup could've used a LITTLE bit more development?), and the angel and demon bits are so much fun that I didn't mind.
Adding the specific flashbacks, and all the changes in the emotional plot in their relationship to each other, essentially created a whole other plot thread too - not one that I'd call a B- or C-plot, because it happens at the same time as the other plot in their scenes, but it creates more tension and more... scaffolding, you could say, for their relationship, which was mostly only visible along the edges of what was happening in the book and in passing as it related to the specific plots relating to the End Times. (That makes it almost sound like it wasn't a love story before! But it was, it's just that it was more about them being drawn together more and coming to a deeper appreciation of one another through the events of the apocalypse, without showing any of the developments in the establishment of their relationship, which already seems to be trundling along in perfect harmony. The series has added in all these points along their personal history that turn it into another kind of love story altogether: a classic romance plot, even if you choose to interpret the love in question as entirely platonic.) Anyway, all of that added material probably made it take a bit more runtime and significance, and Sheen and Tennant are, as everyone has already said including me and them, basically magic together, so I can well imagine them getting more screentime after everyone saw them starting to work together.
Also there's a noticeably reduced presence of the story of Adam's life and the Them. Part of this is probably because so much of the necessary information there is contained in the omniscient narration in a way that is difficult to adapt to the screen without voiceover, which Neil already made liberal use of throughout the whole show. And part of it may well have to do with how expensive and difficult it can be to work with child actors. But regardless, while I think it does still feel a little unbalanced, the gist mostly comes across (the Them-horsemen matchup could've used a LITTLE bit more development?), and the angel and demon bits are so much fun that I didn't mind.