Correct me if I'm wrong, but you are Irish right?
If so, why the finks are you defending the idea of British monarchy?
J'ai du sang français ; je n'ai pas beaucoup de sang irlandais. Qui pensez-vous financé les révoltes jacobites?
Compared to the literally genocidal alternative, the Stuarts weren't anywhere remotely as bad for Ireland; that's why the Irish were on their side to (and after) the end. Most all of the truly nasty treatment of Ireland (as in being murderous and oppressive for the sake of being murderous and oppressive) can be attributed to the Puritans/Dissenters/Presbyterians, or their influence.
The (re)conquest of Ireland started under Henry VIII. Until then Hiberno-Norman Lords and old Gaelic order had a lot of autonomy. A trigger point was the reformation and Henry's own drive for power and asserting dominance. Henry started the execution of clergy members who didnt fall in line, and confiscation of church property and the holding of the Irish Lords (see: surrender and regrant.) Important to note that it was under the Catholic monarch, Queen Mary, land confiscation and plantations really began in earnest, so it isnt a wholly sectarian matter.
The beginning of the Stuart monarchy was no blessing for the Irish. After the failure of the various Spanish intrigues and Rebellions of Red Hugh O'Donnell and Hugh O'Neill during the reign of Bess, the Stuarts continued the policies. Once the Gaelic Lords pulled up stakes for the Continent, James I started giving away land to mostly Scots Lords in huge tracts. These things ripple down for centuries to even the present. For instance, the Dukes of Abercorn (Hamilton's) were granted land in 1612 and they are still one of the largest landowners in NI or that somehow the Earls of Shaftesbury own Lough Neagh, the largest body of freshwater in the British Isles. The private plantations were even more successful and attracted many people to settle.
Side note: It was also James I who started the Irish slave trade to the Caribbean.
Now as a reaction to those conditions, the native Irish were more than willing to take advantage of the unrest in Britain and set out to exact their revenge against the new arrivals. In the Irish rebellions of 1641, massacres of Protestant civilian planters took place in good numbers, even if the early press of the time sensationalized the extent. This was what Cromwell in turn used as justification for his bloody campaign in Ireland. He saw himself as an avenging angel. The Tudors and Stuarts set the stage for Cromwell.
To be continued on how Charles II and James II were also terrible.