Because i don't need to know everything up front. I just need to know enough about you to tell me why I should consider interviewing you and enough for me to prepare questions. I don't run interview for 15 minutes. I run between 1-2 hours interview per candidate. If you try to oversell yourself to me, you are trying too hard. I still go through the interview if I think you are the right candidate to interview even if you did send me a 50-page resume, but that doesn't mean I don't want a briefer CV.
So let me ask you the, is it okay for you to get a 20-page resume then instead of 10? How about this, someone with 40 years of experience and now you get a 40-page resume.
Where is this 15 minute interview idea coming from? I run interviews for 1–2 hours as well. I just don't want to waste that time on large numbers of candidates when I can qualify a smaller number more quickly by having better information up front.
Nobody actually does this, but yes, a 40 page CV would be fine as long as it had a cover letter or summary and it was laid out in a way that I could skim it. I'd prefer the 40 page CV to a 1 page résumé any day, because the 1 page résumé doesn't have what I need to make an informed decision. I can skim a 40 page CV in minutes without chasing anybody for more information and without conducting a 1–2 hour interview.
You've still not provided an argument against more information, just said that you don't value it. There's literally no downside as far as I can see. If you're not interested in certain details then you can just skim over them.
So let me ask you the, is it okay for you to get a 20-page resume then instead of 10? How about this, someone with 40 years of experience and now you get a 40-page resume.