BUT with inert/high CEC substrate, I'd need to feed the plants somehow. Either water column dosing, root tabs, or both. Staying with simple inert substrate, I'd probably just deepen the sand layer to make planting easier and go with root tabs and column ferts.
Oh, I didn't realize you were not dosing the water column, but re-reading your OP I can see that it was implied. Since your objective seems to be simplicity (I'm assuming you're saying that your plant growth/health is meeting expectations), then I guess you are wrestling with which inconvenience is worse: dealing with the dirt mess occasionally or dosing the water column regularly.
In a low-tech tank, you certainly don't need the hefty dosing of a high-tech rank, as you know, and this does lend itself to active substrate, but it is uncontrolled supply and does have a limited lifespan. Do you know what levels of nutrients you currently have in this tank? I'm wondering is something might not be missing/insufficient, such as K, by not dosing the water column at all.
I'd suggest an experiment to see if dosing the water column offers any benefit, to help with your decision: First, measure what nutrients you can to see if those levels are good. Then, add everything you can't measure, plus those you do measure but are deemed insufficient (if any) and wait 2-3 weeks to see if a difference appears in plant performance. I'd probably use the low-tech EI doses in RotalaButterfly to decide how much to dose.
If you see a noticeable improvement, then maybe the inconvenience of regular water column dosing will be worth it for you and you can abandon active substrates. If not, then maybe changing to a less messy active substrate will be good enough, although it will eventually need to refreshed, as well.