I am of the view that opening any kind of bank account is going to get more and more difficult with the relentless KYC requirements.
It costs nothing to keep an account open so why not just leave it open, you never know when you might need it. At the very least no harm could come of it. I am actually the complete opposite to you- i have 2 Bangkok Bank accounts and 2 Krungsri- Now i solely use the Krungrsi ones, but maintain some funds in BB to keep the credit card, not that i ever use it, but its there in an emergency. Actually last week i had to send off payment details for Govt payment, and a day later Krungsri called me to cancel my card due to an unauthorized transaction.
Luckily i still had the BB credit card so i could immediately replace the details for the payment.
Sorry for the long winded blurb. Personally i just dont see the reason in not keeping them- costs nothing or next to nothing and with online APP banking its very easy to manage.