Summary
The Tenth Doctor's explosive regeneration contradicted established Doctor Who lore, but there were reasons for its violence and destructiveness.
The Tenth Doctor's reluctance to change and his aversion to regeneration played a part in the explosive outburst, whereas the Twelfth Doctor's similar resistance had a less detrimental impact. The Tenth Doctor's decision to delay his regeneration and revisit all of his past companions proved to be a more impactful factor than the radiation he had absorbed.
The Tenth Doctor's regeneration into the Eleventh (Matt Smith) was a highly destructive event that defied the established norms in Doctor Who. The sheer force of the explosion completely destroyed the console room of the TARDIS, which was surprising considering that Time Lord TARDISes were expected to withstand regeneration energy. Despite the oddity of this situation, there were explanations offered within the storyline and behind-the-scenes to justify the intense violence of the Tenth Doctor's regeneration.
In his final moments, the Tenth Doctor famously expressed his reluctance to undergo regeneration with the words, "I don't want to go." This sentiment has often been attributed as the main cause behind the explosive nature of his transformation. However, this theory was later contradicted by the Twelfth Doctor (Peter Capaldi), who also resisted change. Although the Twelfth Doctor's regeneration resulted in a powerful explosion that shattered the time rotor, it paled in comparison to the level of explosiveness and destruction witnessed during the Tenth Doctor's regeneration. Nevertheless, there is a logical explanation for this discrepancy.
Reasons For The Tenth Doctor's Explosive Regeneration
The explosion during the Tenth Doctor's regeneration was thought to be because he had delayed the process. This delay indicated that he could no longer hold it in. Though the Twelfth Doctor's delay may seem contradictory, there is more to the story. Peter Capaldi's Doctor delayed his regeneration to save colonists from the Cybermen, and even seemingly died in the process. However, after one final adventure with Bill Potts and the First Doctor, he was convinced to let go and embrace the change. Unlike the Tenth Doctor who resisted until the last moment, stating his desire not to go.
It's important to note that the Tenth Doctor visited all of his previous companions before his regeneration in "The End of Time." Although only those from 2005 to 2010 are shown on-screen, the Eleventh Doctor revealed in the Sarah Jane Adventures episode "Death of Doctor" that he visited every companion in the Doctor Who universe. This prolonged delay in regeneration explains the explosive change. It is also a more compelling reason than the radiation absorbed to save Wilf, as the Doctor had always absorbed exotic radiation without such explosive effects.
What Ten's Violent Regeneration Really Meant
The violent regeneration of the Tenth Doctor was a practical way to make room for the new era of Doctor Who with Steven Moffat and Matt Smith. In "The End of Time", the Doctor's regeneration was the culmination of his refusal to accept his fate in his final specials. The Tenth Doctor's determination to avoid death resulted in the destruction of the TARDIS, symbolizing his resistance against his impending end.
The Tenth Doctor's resistance to death may play a significant role in the upcoming 60th anniversary episodes of Doctor Who, where David Tennant returns as the Fourteenth Doctor. It is evident that something has gone wrong, and the Doctor might be tested by being offered the opportunity to be the Tenth Doctor once again. Hopefully, this time the Doctor will be able to overcome their fear of change and regenerate into Ncuti Gatwa without causing such immense damage to their beloved TARDIS.