Applying pressure through substantial incentives is probably the better way of expressing it. I guess incentivizing someone enough is the same as forcing them but I digress. Why substantially incentivize locals to have children, when there's strong worldwide negative correlation between income/development and child birth? Why are local children inherently better than immigrants? To the extent that the society functions well and immigrants integrate into the broader country, what difference does it make?
I would further argue that "bringing in immigrants" isn't the "easy way out" or even likely the "cheap way out" but rather probably more challenging. Creating a society that deals well with the gaijin isn't easy.
I see no evidence that free daycare or longer parental leave actually incentivize adults to have children. The birth rate in Finland is 1.49 and falling rapidly, Sweden and Norway are 1.8ish. Iceland is 1.75. Germany is 1.57. Spain is 1.34. These places have incredibly generous programs and are well below the replacement rate of 2.1.
Finland's mat leave is 4.2 months and pat leave is 2.2 months and offers public daycare centers. If that's not long enough or free enough to boost their brith rate over 1.49 I'm not sure what you'd suggest.
Yes, mat/pat leave is great, and should exist. So should free daycare. However, I don't see any evidence that'll move the needle. If anything, it appears that pushes the birth rate further down being correlated broadly with increased development.