Nice price close for POS, page-54

As an example, when traded from a linked savings account (the CBA account in that settlement funds flow from/to), CommSec's internet preferred rates are:
$19.95 (Up to $10,000)
$29.95 (Between $10,000 and $25,000)
0.12% (Over $25,000)
This is all DIY.

CommSec's over the phone rates are:
$59.95 (Up to $10,000)
0.52% (Between $10,000 and $25,000)
0.49% (Between $25,000 and $1,000,000)
0.11% (Over $1,000,000)
This is materially higher that their internet rates and more in line with your current arrangement (0.5%).
(https://www.commsec.com.au/support/rates-and-fees.html)

If you're out of town often, don't trade very often (take long-term positions) or otherwise distracted, then I can certainly see the merits of consciously paying the extra for full service broking.

One benefit of full service is that a human is actively managing the buy/sell order, tweaking the order as required (with your permission) for a known fixed %. Internet trading orders can be much more rigid and rules based. If you tweak a partially filled order (in CommSec, for example), it can amount to a new order and can impact on the rate that ends up being charged, depending on the value of the partial fill and also the subsequent manual change you made to unfilled order that is subsequently filled. Some brokers have systems that overcome this, though.