Realtor advises against making official lowball offers - your take?

[Ivan Jouikov]

In a search for my own property I finally got one under contract. It's a short sale and they've got 30 days to get the lien holder approval (they actually advertised it as pre-negotiated, but wanted 90 days for this).

In the meantime, I want to keep searching and making offers on properties.

My Realtor doesn't seem to be inclined to make official low ball offers - his reasoning is that it's "insulting" to the seller's agent and wastes everyone's time. This is a conversation we had over the phone yesterday:
Me: I don't want to waste your time and money by driving out and looking at all these properties, considering we already got one under contract. I still want to keep looking though, that's why I want to make some lowball offers on other properties.
Him: that's fine, but sending an email message saying "my client wants to offer $50k less than you're asking - how do you feel about that - should we even submit an official offer?" is far more effective than straight out shooting an official offer for a lowball price. Otherwise the agent will think "what are you stupid - why are you wasting my time with this"?

Any advice? Is he trying to save himself from doing extra work? As far as I know, an official offer MUST be passed onto the owner, whereas a lowball "email" offer doesn't have to be.

Thanks!