The OT Law can helpfully be understood as a hard boundary over which God's people should not cross. Kind of like the walls of a play-pen - outside is simply unsafe, so best stay inside.
Yet might life outside be possible? Can God be at work 'out there'? What if God could enable people to know in their hearts what was right and what was wrong: could they then venture out?
God told Jeremiah about a new deal where he would do exactly that (Jer 31:31 - 34). It would not be like the old law, but instead God's ways would be direct in peoples minds and hearts. He also told Joel about the special day when His Spirit would be poured out onto people, enabling them to speak God's works, to know His plans and mind.
Equipped with the Spirit we can venture out, beyond the confines of the play-pen. Note how God explicitly tells Joel this will be for men and women - this was not a male only thing. Rather all people, regardless of gender or background could receive the Spirit and take part in His purposes.
Pentecost - plenty of reason to be a people of hope!