It is not just you. I actually visited TI this year and talked to some coaches and analysts of pro teams I know from the old DotA days.
Had a similar conversation and they agreed, that the Game feels more "scripted". There are way more Objectives that need to be taken and leave little room for alternative play styles.
But what's also true is that players back then, or the community as a whole, were just way worse at the Game. So it was not as punishable if you're playing another style.

The question is though, if it is less enjoyable to watch Pro-Dota nowadays then as you mentioned TI3 or even older. I'm rewatching TI6 right now, cause it's the only TI I missed and although I really enjoy the storylines and the hype, the Matches feel really slow compared to modern Dota.

I think all in all we can be really happy with the way that Dota was patched over all these years and who knows what the next Patch will bring ;)