Why was President Franklin Pierce a good president?
To the extent Franklin Pierce could be considered to have been a "good" president of the United States, such a conclusion would hinge overwhelmingly on an assessment of intent. As president, Pierce was overly-occupied with issues of unity, both within the Democratic Party and with respect to the nation as a whole. While that commitment to party and national unity was commendable, it also allowed for a serious deficiency in the very qualities of leadership required of any American president. Rather than assess the options and choose and implement those that best advanced the interests of the nation he was elected to lead, President Pierce pursued accommodationist policies at the expense of the greater good.
President Pierce sought to reform the institutions of government, and to reject policies that threatened the fragile unity of the United States. In so doing, he allowed for the continued exposition of practices that would ultimately lead to the very dissolution of the union that he so feared -- a dissolution aborted solely through the protracted and bloody struggle by Union to prevent southern secession. In other words, slavery, the most important political and moral issue of the time, continued to go unaddressed by virtue of the president's unwillingness to cast his lot with those who favored abolition at the expense of those factions of his party, and they were formidable, that opposed abolition. Had Pierce stood firm against the institution of slavery, it is entirely possible the Civil War could have been avoided. That, however, is placing more of the responsibility for that abhorrent practice with his single presidency than is warranted given the failure of the Founding Fathers to resolve the question during the nation's birth.