6. Mix of styles
One of the best things about Tom Baker's era isn't just how long it is. Due to changing script editors and producers, Tom Baker's seven seasons feature a great mix of styles. And these different styles would've appealed to different audiences.
For example, there would've been many children who loved the monsters and the horror that defined Baker's first three seasons. In fact, for many, it would've been their family-friendly introduction to the horror genre. But there also would've been children who would've been too scared to watch because of it.
Those children probably preferred the lighter adventures that the Doctor shared with his robot dog K9. They may have enjoyed the overall lighter tone and more comedic adventures that Baker's fourth to sixth seasons brought.
Perhaps there are those who even fondly remember the distinctive style of Tom Baker's final season. While being radically different to what came before - featuring a harder science approach, less comedy and even a completely new costume - it's still a strong season in its own right, and definitely has its fans.
Regardless, there's no doubt that the mix of styles would've ensured that Tom Baker's Doctor was loved by many. They may not have watched or enjoyed every single episode of his Doctor, but they'd remember Tom Baker's Doctor being at the center of all of those stories.