The new TIE is very handy. Simply a credit card sized ID and is accepted by hotels and internal airlines instead of a passport as ID. Yes, some say they will accept a driving licence but none of the hotels I've stayed at in Spain would and required a passport. Vueling to Mallorca wouldn't accept the Spanish driving licence either and wanted a DNI or passport although Iberia to Barcelona a while back were happy with driving licences.
When hubby bought a car a while back, they wanted green residency card, padron or utility bills. Just bought a new one and the TIE was all that was required as it has your address on as well as your NIE. (in both Spanish and English).
We changed ours purely because our passports were due to run out and the bank informed us our account would be locked until we provided up to date ID. As we only had 6 weeks before they expired, we got the TIE which the bank accepted (not the green card or a driving licence, though, as neither of them were on the list of acceptable documents). As it was the passport was very quick and we got them back in 4 weeks but they were saying allow 11 weeks at the time.
The cost for the TIE is €12 and it is free to renew when it does run out so hardly going to break anybody's bank, I hope. Unlike the passports which cost £105 each.
No, we've never been stopped and asked for ID. The only time was when I got my second vaccine and a jobsworth asked for photo ID. In that case the driving licence was accepted but nobody else was asking for ID.
We were surprised at how easy it was to change it. A simple hand in the forms (and there are plenty of advice sites showing how to fill the form in) and a trip to the bank to pay the €12 tax plus go back in 3 weeks to collect the card.
We weren't going to change them but it was just the bit with the passports running out that decided us. Great now with just another credit card thing to carry around. Hubby has one of those RFID holders which has the driving licences, TIE cards, SIP cards, bank card and credit card in them.
As cloudnine says he can't find the green A4 certificate, it would only be replaced by a TIE anyway. Yes, it's only valid 10 years but that's because the photo needs updating (same as your passport).
Some things are easy and it is also easy to say why bother. Glad we got ours before they do make it compulsory and the system gets overloaded again.