The default is “no”. Without explicit consent you can’t do a lot of things.
You can’t have a default yes, because how can you agree with consent but automatically to everything?
And if it’s a no, are you saying you can’t ask a user for permission to use their data for a specific purpose?
And if you can ask, that’s what we have right now.
Other processing (like after value is read) can happen under GDPR if the data is personal data.
Note that you don't comply with EU directives anyway - you comply with actual laws of actual countries, and the EU process helps them to mostly agree with each other. Did countries replace their ePD-based laws with GDPR-based laws? My understanding is they did.
ePD is still active and national laws implement it. GDPR itself is not implemented by national laws as it's EU regulation rather than EU directive. Member States primarily repealed their DPD-based laws after GDPR and implemented various things that GDPR allows (like Article 23 restrictions). Some countries may have explicitly imported GDPR into their own law due to how their own legalization works. Like that's why UK DPA was originally pretty much just copy of GDPR.