Would it tho?
Because even as the home team, the toss is essentially 50/50. Why would you make a pitch where, if you lost the toss, you would struggle?
The home team has an advantage on their surfaces because they believe they can win/draw on it regardless of the result of the toss. Letting the away team pick if they bat or bowl first won't change that.
It would remove the abundance of win-toss-win-match pitches, that's a plus. And it would discourage sides from producing the kind of pitches that sides like Pak and India exploit - bat first win, bowl first draw. But otherwise, overall, I doubt you would see less home-side friendly pitches.
I'm all for the idea tho. I like removing the emphasis on the toss and toss-dependent pitches. If the pitch is such where the decision is obvious before the toss, the away side can see the pitch, decide what they want to do, and pick a side. The home-side can then predict what the away side will do and prepare for that, and be ready to struggle in the first innings.
To avoid that, they will have to create a pitch where the choice between batting or bowling isn't so obvious, and where doing either will not be massively beneficial. This encourages more balanced pitches and more balanced cricket IMO.
And even if it doesn't, you'll see the side bowling first on a road pick 5 bowlers, or the batting side on a minefield go with extra batting, and we won't get a massively lopsided match.