For the purpose of security, transactional isolation, and even just logical simplicity; I agree that you should consider one Azure SQL database per tenant, especially if you serve and international client base. If the databases are contained in the same resource group (this is advised), the databases can share an elastic DTU pool.
Another benefit of the one database per tenant model is that, if a tenant has a special legal requirement or corporate policy regarding where their data is physically hosted, then you can simply move their database to another region. However, a single DTU pool cannot span regions, so this will require at least one pool for each region.
"Do not seek to follow in the footsteps of the wise. Instead, seek what they sought." - Matsuo Basho