So it didn't bother me! GRRM has said that the ending will be the same, TV vs. books, but the path to the end may be a little different. That's fine and understandable. But yes, a more focused TV series really shows what storylines and characters in the books are rather pointless.
Actually, I meant it the other way round. I feel most of the prominent changes from the book which altered existing story lines have been detrimental.
Jamie was cool in seasons 1-3, changing from a flashy villain to a tragic hero. The height of this change was the bath scene with Brienne in S3. Once he was reunited with Cersei the showrunners got scared from seperating them in any meaningful way and his cool book character was ruined. We got the dumb and ultimately pointless rape scene in front of Joffrey's body. The stupid trip to Dorne. Now he is Cersei's butler.
Dropping Vargo Hoat, while it made sense from having too many characters for a TV show, was also a big stupid mess. Because they dropped Hoat, but stilll wanted the bit about cutting off Jamie's hand, they had a Bolton subcommander do it instead. But the whole point of Hoat disarming Jamie was that he suspected something was up between Roose Bolton and Tywin Lannister. Since Hoat had already switched sides once going from Tywin to Robb Stark, he could never go back to Tywin. For this reason he cut off Jamie's hand to drive a wedge between Bolton and Lannister. Ultimately this did not work, but it was more than just savagery. Roose Bolton was able to convince the Lannisters he had nothing to do with it.
In the TV show, however, it IS a Bolton guy who offs Jamie's hand. But Roose is still able to convince he had nothing to do with it. How ??? Why ??? He doesn't even flay the man who did it. Instead Bolton sends the same man to the Night's Watch to kill Jon Snow. Or maybe to kill Bran, I don't recall.
Then you have Sansa and Littlefinger's altered story line. Instead of the fake Arya story line and Sansa rallying the vale to tip the balance for Jon, Lillefinger sells Sansa to Ramsay for no tangible reward. Then she gets raped and degraded after her character already sorta went through this with Joffrey. This leads to the nonsensical situation of the same character having to do both the fake Arya bit and the Sansa bit. So she goes to Jon Snow but also has the Vale knights on standby close by, but no one knows this or notices this until the moment the Vale knights appear on the battlefield. And the show attempts to fix this blunder by an offhand "oh sorry I didn't tell you about the huge army I had waiting half a day's ride away". Jon answers with a "no biggie sis. (probably thousands of my men died needlessly but whatever)"
It is possible storylines which have been dropped entirely are indeed pointeless in the books but time will tell ( Aegon? ).
