It would be easier but not more desirable.
It's easier because the person can't return the book, they know for sure the grade they are getting, and it helps avoid further damaging it when you send it.
However, raws are more desirable because they will atract the entire fanbase. Some people don't want CGC slabs, some want to read the original book, and some hope to buy a raw book and then improve it in various ways to hopefully get the best grade possible. And those who prefer a CGC'd book can still CGC it themselves. So you widen your market.
By selling raw you also get to sell it right now, without having to wait 6 months for the book to come back and without having to invest in professional grading (and it also avoids terrible scenarios of CGC losing your book or damaging it, or it being damaged while in transit, all of which has happened). You instead pass on the burden of it being professionally graded to the buyer while you reap your profits quicker. One of the largest dealers in rare comics is Harley Yee and he keeps most of his stuff raw, it's more profitable. But he sells at shows where people can check the comic before buying it, so he avoids returns that way.
Also, from what it seems, unless you are referring to books that only sell really well in 9.8 CGC holders (where one can only get that by getting it graded), most books sell as much raw than graded (especially when you remove the cost of grading from the price it sold at). Or they sell even better raw (example below)
The main reason to get a book graded is if you are a betting man and hope for a 9.8 on a book that has few of those, or if you simply want to avoid people sending you back books if they aren't happy with them.