1. It is quite harmful to one's privacy and becomes an impediment to BTC censorship resistance
It is why we have changed addresses and there is advice to use changed addresses and avoid to reuse addresses.
2. It can leave one open to niche attacks and one becomes vulnerable to these cyber thieves who will extract private keys from signatures after a transaction has been made.
Do you know that a process from Private key > Public Key > Public (Receiving) address is a one-way process.
3. Quantum computers could extract private keys if these addresses are re used.
Quantum computers are things used to spread fear about Bitcoin. It started years ago and now still can not break Bitcoin private keys. Do you really think that Bitcoin protocol won't be upgraded over time in order to be better for itself and to protect itself from potential attacks, exclusively Quantum computers.