Talking about averages is really tricky when the total amount of code/libraries is growing rapidly. In general though I think all of the following are true:
1. The number of high-quality libraries available has increased substantially.
2. The variance has also increased substantially.
3. The AVERAGE quality of polished libraries has gone down.
Basically, the number of open source libraries has exploded over the past decade or so but the majority of new libraries are of low quality because they are slapped together or only half-baked and then abandoned. But it is easier than ever to find high-quality open source libraries for any use case you can think of. In other words, things have never been better but you cannot assume that a library is of a reasonable quality just because it is published as an open source library.
1. The number of high-quality libraries available has increased substantially. 2. The variance has also increased substantially. 3. The AVERAGE quality of polished libraries has gone down.
Basically, the number of open source libraries has exploded over the past decade or so but the majority of new libraries are of low quality because they are slapped together or only half-baked and then abandoned. But it is easier than ever to find high-quality open source libraries for any use case you can think of. In other words, things have never been better but you cannot assume that a library is of a reasonable quality just because it is published as an open source library.