No, it's not "useless" . .
First, except for a brief period when only one vendor had them, going by the PCPartPicker price history, the 4500 has always been less than MSRP.
Second, for someone already on AM4, and with a low-to-mid 1st gen Ryzen CPU and having to fit a really tight budget, it's an upgrade. I know one person for whom this is the case, and the extra (at this time, extra $25) for the 5500 would actually be problematic.
The real issue is, as is correctly pointed out, is the 5000 series. The 5500 is usually available for not much more. That's what can cannibalize the sales of the 4000 series unless the price drops more, relative to the 5500.
AND.. on a final note, I really am looking forward to the update to the CPU hierarchy to see exactly where these two slot in, relative to other low-end Ryzen chips, performance-wise.