Yes, the vouchers are a nice perk, but as Flying Yazata points out, the AY route network is very limited. Thus the vouchers are worthless, if you want to go to South America, Africa or somewhere else where AY doesn't serve. Imagine you would live in an outstation (e.g. TYO). You could only use that voucher to go to HEL.
I think people might not understand the value of Avios. Avios are far from perfect, but they're infinitely more useful on a global scale than Finnair Plus points. An example redemption that I recently did - DOH-BKK in QR Y or J:
- AA: 25 or 40k (includes a feeder in the middle east if necessary)
- AY: 75 or 154k (ay.com was broken, this is what the phone agent told me)
- BA: 30 or 60k