I'm on the fence. Evidence from phones has both secured convictions and exonerated defendants in the past. So I can see why it can provide essential evidence.
That said, we need to improve the system whereby evidence is extracted. It's horrendously unfair to keep someone's phone for months. There must be sufficient resources to extract evidence in under a week or less.
Asking how we convicted people before the advent of phones, well often we didn't. And nowadays so many people live their lives on their phones.