It is probably down to what daveybjones999 and Channel72 said above.

I would also say it seems some of the high-ups at Lucasfilm probably think of Ewan as being Obi-Wan Kenobi, more than Alec Guinness was. Likely on being the more modern performer, and that is who they have likely worked with. More so in that Ewan was also a producer on the recent Kenobi series too.

It did irk me when director Deborah Chow said this about Ewan - “He to me, is Obi Wan”, in the “Obi Wan Kenobi: a Jedi’s Return” documentary, with an emphasis on “is”.

It also didn’t help that the Kenobi series felt more like a Prequel style series than a bridge between the Prequel Trilogy and the Original Trilogy, and that it was meant to take place half way between the two trilogies in the time line, but it just didn’t feel like that, to me.

I did appreciate TFA going to the lengths they did of mixing both Ewan and Alec Guinness voices in TFA, for the “Rey, these are you first steps” line: https://www.youtube.com/watch?v=ygFoN3hKi20