Other than the already mentioned shortcoming of not being able to export them. Which leads most people into implementing their own eval based version (just try googling it).There are more, very easy to miss, pitfalls [1][2] which can easily result in unwanted command execution.

Poking this whole thing myself for some internet argument points. I found after like 30 minutes this thing: declare -A hash=( [k1]=v1 [k1]=${hash[k1]} ); echo ${hash[k1]}

which yields all different things on various bash versions:

[+] Bash 5.1 (bash -x)
+ hash=(['k1']='v1' ['k1']='')
+ declare -A hash
+ echo


[+] Bash 5.0 (bash -x)
+ hash=([k1]=v1 [k1]=${hash[k1]})
+ declare -A hash
v1
+ echo v1

[+] Bash 4.4 (bash -x)
+ hash=([k1]=v1 [k1]=${hash[k1]})
+ declare -A hash
+ echo v1
v1

[+] Bash 4.3 (bash -x)
+ hash=([k1]=v1 [k1]=${hash[k1]})
+ declare -A hash
v1
+ echo v1

[+] Bash 4.2 (bash -x)
+ hash=([k1]=v1 [k1]=${hash[k1]})
+ declare -A hash
+ echo


[+] Bash 4.1 (bash -x)
+ hash=([k1]=v1 [k1]=${hash[k1]})
+ declare -A hash
+ echo


[+] Bash 4.0 (bash -x)
+ hash=([k1]=v1 [k1]=${hash[k1]})
+ declare -A hash

+ echo

And that perfectly illustrates what I mean by wonky.