If you're not OK in melee at higher levels without shillelagh, then you're probably not using wild shape.
Druids are not typically melee combatants, except through becoming a bear. (Consider the AD&D druid... leather armour, scimitar, moderate hit points. That's not a great front-line fighter).
Shillelagh is best at low levels, where it gives your druid a magic weapon - for a minute, without concentration. That, by itself, is really good. You can deal more damage to creatures with resistance when otherwise you'd struggle. What makes Shillelagh problematic in a balance way is that it allows you to use your spell-casting stat rather than Strength/Dexterity to attack, and that it stacks with all other bonuses to attack. Multiclass with shillelagh? Things get tricky.
But Shillelagh isn't actually a problem. The misconception here is that druids (sans wildshaping) are good in melee. They're not. The two paths are spellcasting and wildshaping.
Shillelagh is useful when you're fighting fiends and undead that are resistant to your usual attacks, but it's also a signal about the role of the druid.
